뒷조사 (dwitjosa)

뒷조사 (dwitjosa) means looking closely into a person or a matter and digging things up without the other person noticing. Watch enough Korean dramas and you’ll see that the scenes where this word appears are almost always the same. A mother who has been quietly studying the woman her son brought home calls in her secretary. A detective spreads out five years of a suspect’s bank records. Or you realize that a coworker already knows the whole story of your previous job. They all have one thing in common: the moment the word is said, the air on screen drops a few degrees.

On its own, 조사 (josa) is a neutral word. Police 조사 (investigate), scholars 조사 (research), broadcasters 조사 public opinion (poll). But the instant 뒷- (dwit-) is attached to the front, the character of the word changes. 뒤 (dwi) is behind — your back, the side the other person can’t see. So 뒷조사 (dwitjosa) isn’t “finding something out,” it’s “finding something out without the other person knowing,” and a verdict is already baked in: this is not aboveboard.

That’s why the target of this word is almost always a person. You don’t say you did 뒷조사 (dwitjosa) on an object or a price. The verbs it pairs with are narrow, too — 뒷조사를 하다 (hada) / 당하다 (danghada) / 받다 (batda) / 의뢰하다 (uiroehada) / 부탁하다 (butakhada). The very fact that 당하다 (danghada) and 받다 (batda) attach so naturally tells you what kind of word this is. Nobody “gets subjected to” a good thing.

One more thing. Korean speakers rarely use 뒷조사 (dwitjosa) about their own behavior. The moment you say it, you’ve cast yourself as someone with something to hide. The word is normally used when pointing out what someone else did, or when jokingly putting yourself down a notch. That sense of temperature is the heart of today’s post.

Checking It in the National Institute of Korean Language Dictionary

The National Institute of Korean Language’s Basic Korean Dictionary defines the word like this.

뒷조사 「명사」 (noun) 겉으로 드러나지 않게 어떤 사람이나 일에 대해 자세히 살피고 알아봄. 또는 그런 일. Examining and finding out about a person or matter in detail, in a way that does not show on the surface; or such an act. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)

Notice that the condition “겉으로 드러나지 않게 (without it showing on the surface)” sits at the very front of the definition. What matters in 뒷조사 (dwitjosa) isn’t the depth of the investigation but its secrecy.

The dictionary also carries translations into several languages.

[en] secret investigation — An investigation into someone or something without anyone else’s knowledge, or the act itself. [ja] ないさ【内査】。ないてい【内偵】 — 表に出ないように、ある人や物事について詳しく探り、調べること。また、そのこと。 [es] investigación secreta, investigación clandestina — Averiguación o acto de averiguar meticulosamente sobre un asunto o una persona secretamente. [zh] 秘密调查，暗查 — 对某人或某事进行隐秘详细的调查了解；或指那样的事。 — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)

A Portuguese equivalent isn’t listed in this dictionary. For reference, our own rendering would be something like investigação secreta / investigação sigilosa (noting clearly that this is our translation, not dictionary content).

Below are the actual usage examples from the same dictionary, quoted as they appear, with a note on the situation each one paints.

그는 회사 동료가 자신의 뒷조사를 하고 있다는 사실을 우연히 알게 되었다. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)

Geuneun hoesa dongnyoga jasinui dwitjosareul hago itdaneun sasireul uyeonhi alge doeeotda. — “He happened to find out that a coworker was digging into his background.”

A classic office-drama moment. The key phrase is “우연히 알게 되었다 (happened to find out).” Since 뒷조사 (dwitjosa) is by definition something done so as not to be caught, the moment it is caught becomes the incident.

범인은 사원 중 한 명이니 전 사원들의 뒷조사를 해서 범인을 잡아내게. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)

Beomineun sawon jung han myeongini jeon sawondeurui dwitjosareul haeseo beomineul jabanaege. — “The culprit is one of the employees, so look into all of them and find whoever it is.”

This is the tone of a superior giving orders to a subordinate. The ending -게 (-ge) belongs to the 하게체 (hagechenom) speech style used downward in rank — it fits a company president speaking to a department head, or a squad chief speaking to a detective.

아무런 이유 없이 은밀하게 민간인의 뒷조사를 하는 것은 잘못된 일이다. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)

Amureon iyu eopsi eunmilhage mingininui dwitjosareul haneun geoseun jalmotdoen irida. — “Secretly investigating private citizens for no reason at all is wrong.”

This example shows the moral weight of the word straight on. It’s the kind of sentence you’d see in a news report or an editorial, and paired with 민간인 (minganin, private citizen) it immediately becomes a story about abuse of state power.

뒷조사를 의뢰하다. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)

Dwitjosareul uiroehada. — “To commission a secret investigation.”

People sometimes do 뒷조사 (dwitjosa) themselves, but very often they hand it off to someone else. That’s why dramas are never short of 흥신소 (heungsinso, private information agencies), 심부름센터 (simbureumsenteo, errand agencies), and private detectives.

뒷조사를 당하다. — National Institute of Korean Language, Basic Korean Dictionary (krdict.korean.go.kr)

Dwitjosareul danghada. — “To be secretly investigated.”

The fact that 당하다 (danghada) attaches means this is perceived as something done to you, as harm. You 당하다 a scam, you 당하다 being ignored, and you 당하다 a 뒷조사.

A Real Conversation

Scene: The subway home on a Friday evening. Emily is scrolling three years deep into the social media of the guy she’s meeting on a blind date tomorrow.

Emily: 오빠, 이 사람 3년 전에 제주도 살았대. 사진 다 봤어. Jun-kyung, this guy lived on Jeju three years ago. I’ve seen all his photos.

Jun-kyung: 야, 그거 완전 뒷조사잖아. 만나기도 전에? Hey, that’s straight-up snooping. Before you’ve even met him?

Emily: 뒷조사는 무슨. 그냥 공개된 계정 좀 본 건데. Snooping, my foot. I just looked at a public account.

Jun-kyung: 상대가 알면 어떨 것 같아? 나 같으면 뒷조사 당한 기분일걸. How do you think he’d feel if he knew? I’d feel like I’d been investigated.

Emily: …그런가. 좀 찔리네. 딱 여기까지만 볼게. …Maybe. Okay, that stings a little. I’ll stop right here.

Jun-kyung: 어차피 내일 만나서 물어보면 되잖아. 폰 넣어. You can just ask him tomorrow anyway. Put the phone away.

These Uses Sound Off

✗ 면접 준비하면서 그 회사 뒷조사 좀 했어요. (Myeonjeop junbihamyeonseo geu hoesa dwitjosa jom haesseoyo.) ✓ 면접 준비하면서 그 회사 좀 알아봤어요. (Myeonjeop junbihamyeonseo geu hoesa jom arabwasseoyo.) — “While prepping for the interview, I looked into the company a bit.” → Reading a website and a job posting is a public activity anyone does. Using 뒷조사 (dwitjosa) here makes you sound like someone who went poking around inside the company in secret — you’ve made yourself look suspicious for no reason.

✗ (to your boss) 부장님, 제가 그 거래처 뒷조사 좀 해 봤습니다. (Bujangnim, jega geu georaecheo dwitjosa jom hae bwatseumnida.) ✓ (to your boss) 부장님, 제가 그 거래처 평판을 좀 알아봤습니다. (Bujangnim, jega geu georaecheo pyeongpaneul jom arabwatseumnida.) — “Sir, I looked into that client’s reputation a bit.” → Using this word in a work report implies you didn’t run a normal check but dug something up unofficially — or, at worst, illegally. At the office, 알아보다 (araboda, to look into), 확인하다 (hwaginhada, to confirm), and 조회하다 (johoehada, to run a check) are the safe choices.

Example Sentences by Situation

① Calling out what someone else did — the moment you realize your new team leader knows about your old company.

제 전 직장 얘기를 어떻게 아세요? 혹시 뒷조사하신 건가요? Je jeon jikjang yaegireul eotteoke aseyo? Hoksi dwitjosahasin geongayo? (How do you know about my previous job? Did you… look into me?)

Putting 혹시 (hoksi, by any chance) at the front softens the direct accusation by one degree. Even so, the question lands with real weight.

② Playfully putting yourself down — when a friend catches you remembering their favorite band, their coffee order, and even their allergies.

내가 너 뒷조사한 거 아니고, 그냥 다 기억나는 거야. Naega neo dwitjosahan geo anigo, geunyang da gieomnaneun geoya. (It’s not like I was investigating you — I just remember everything.)

Here you raise the word in the negative first and laugh it off. This is also the everyday use in which the word appears most often in real Korean conversation.

③ Handing it to a third party — trying to track down a seller after being scammed.

결국 흥신소에 뒷조사를 의뢰했다고 하더라. Gyeolguk heungsinsoe dwitjosareul uiroehaetdago hadeora. (I heard they ended up hiring a private agency to dig into him.)

The ending -더라 (-deora) is used to relay something you saw or heard yourself. It fits perfectly when passing along someone else’s story.

Polite Form, Casual Form, and Similar Expressions

뒷조사 (dwitjosa) is a noun, so it carries no politeness level on its own. The level is decided by the verb that follows.

Casual (반말, banmal): 야, 너 나 뒷조사했어? (Ya, neo na dwitjosahaesseo?)
General polite (두루높임, durunopim): 혹시 저 뒷조사하셨어요? (Hoksi jeo dwitjosahasyeosseoyo?)
Formal (격식체, gyeoksikche): 저에 대해 따로 알아보셨습니까? (Jeoe daehae ttaro araboshyeotseumnikka?)

In practice, though, it’s rare to ask a superior or a business partner point-blank, “뒷조사하셨어요?” Saying it defines the other person as someone who digs around behind backs, and the relationship can end right there. In formal settings, the Korean-sounding move is to swap the word out, as in the third sentence.

Expression	Temperature / Intensity	Where it’s used
뒷조사 (dwitjosa)	Chilly and negative. Digging in secret	Calling out someone’s behavior; crime and office dramas
조사 (josa)	Neutral	Official procedures, research, news reporting — anywhere
알아보다 (araboda)	Light and neutral	Everyday talk. “그 식당 좀 알아봤어 (I looked that restaurant up)“
신원 조회 (sinwon johoe)	Stiff, official term	Hiring, security, and other procedural checks
사찰 (sachal)	The heaviest. Power, applied systematically	News and politics. Not used in everyday conversation

Cultural Background — Words That Begin with ‘뒷-’

Korean has a whole family of words built with 뒷- (dwit-): 뒷담화 (dwitdamhwa, talking trash about someone who isn’t there), 뒷거래 (dwitgeorae, a shady deal made in secret), 뒷돈 (dwitdon, money that never makes it onto the official books), and of course 뒷조사 (dwitjosa). Not one of them is aboveboard. Here 뒤 (dwi) isn’t a simple direction but the place other people’s eyes can’t reach, and the sense of “something that happens there” is welded right into the word. Learn this one rule and you can usually guess the temperature of any 뒷- word you meet for the first time.

In dramas, 뒷조사 (dwitjosa) is practically a genre device. In shows featuring 재벌 (jaebeol, conglomerate) families especially, there’s almost always a scene where someone orders a quiet dig into the family background, education, and past of whoever the son or daughter is dating. An envelope slides across a table, and out come photos and documents. Crime dramas use it from the opposite side: when a detective personally digs into someone an official investigation can’t touch, a colleague warns him, “그거 뒷조사잖아 (That’s snooping, and you know it).” Same word — a tool of power on one side, rule-breaking righteousness on the other.

In daily life, it lives much more lightly. Skimming a blind date’s social media, googling the name of a new boss — people laugh and tell each other, “완전 뒷조사네 (that’s full-on snooping).” This is an age when the tool isn’t a real private agency but a search bar. Still, even used with a laugh, the word keeps a layer underneath it: “something the other person wouldn’t like if they knew.” That’s why a learner who uses this expression well doesn’t just look good at Korean — they look like someone who understands where Korean people draw the line around privacy.

Today’s Quiz

Which of the following situations best fits the word 뒷조사 (dwitjosa)?

① You carefully read through the job posting and salary information for a company you’re thinking of moving to. ② Parents secretly hired someone to look into the girlfriend of their son, who is about to get married, without anyone knowing. ③ You asked a friend how far the material for the exam goes.

See the answer

Answer: ②

뒷조사 (dwitjosa) has two conditions: the target must be a person, and it must happen without that person’s knowledge. Option ② meets both, and since the work was handed to someone else, it even matches 뒷조사를 의뢰하다 (dwitjosareul uiroehada, to commission a secret investigation) exactly. Option ① is checking publicly available information anyone could see, so 알아보다 (araboda) is the right word, and ③ was asked out in the open, so 물어보다 (mureoboda, to ask) is plenty. If it wasn’t done in secret, it isn’t 뒷조사 (dwitjosa) — no matter how deeply you looked.

Definitions and example sentences are from the National Institute of Korean Language’s Basic Korean Dictionary (krdict.korean.go.kr); that portion of this post, including our translations, is licensed under CC BY-SA 2.0 KR.