Not all intransitive verbs are alike. Compare 아이가 뛰어요 ("the child runs") with 문제가 생겨요 ("a problem arises"). Both have a single subject and no object, but the subjects play opposite roles: the child does the running — it's an agent — while the problem doesn't do anything; it's the thing that comes into being. Verbs of the second type are called unaccusative — intransitives whose sole subject is a patient (an undergoer), not an agent. This distinction is invisible in a dictionary, but it has a very practical consequence: unaccusative verbs behave like ready-made passives, so they cannot take passive marking. Trying to passivize them — 생겨지다, 나지다 — is one of the most common over-corrections learners make once they've drilled the passive. This page explains why the slot is already full.
What makes a verb unaccusative
A passive works by taking a transitive verb, promoting its object to subject, and pushing the agent into an oblique 에게/에 phrase: 경찰이 도둑을 잡다 → 도둑이 (경찰에게) 잡히다. The whole point of the operation is to move a patient into the subject slot.
Unaccusative verbs have already done that for free. Their single argument is a patient sitting in subject position from the start. 문제가 생기다 — the problem (patient) is the subject. 돈이 떨어지다 — the money (patient) is the subject. There is no object waiting to be promoted and no agent waiting to be demoted, because the verb never had them. So there is simply nothing for a passive to do. The passive slot isn't just optional here — it's structurally already occupied.
The core unaccusative verbs
A handful of very high-frequency verbs are unaccusative, and you'll use them constantly to narrate events. Learn to recognize them as a class.
| Verb | Meaning | Typical subject (patient) |
|---|---|---|
| 되다 | become, get done | 겨울이, 준비가 |
| 생기다 | arise, come to exist | 문제가, 일이 |
| 나다 | occur, break out | 불이, 소리가 |
| 남다 | remain, be left | 시간이, 음식이 |
| 사라지다 | disappear | 통증이, 흔적이 |
| 떨어지다 | fall, run out | 돈이, 배터리가 |
Watch how each puts the affected thing in the subject slot with 이/가, and how none of them has — or wants — an agent.
갑자기 문제가 생겼어요.
gapjagi munjega saenggyeosseoyo
A problem suddenly came up.
돈이 다 떨어졌어요.
doni da tteoreojeosseoyo
The money has all run out.
좋은 생각이 났어요.
joeun saenggagi nasseoyo
A good idea came to me.
옆집에 불이 났어요.
yeopjibe buri nasseoyo
A fire broke out next door.
벌써 겨울이 됐어요.
beolsseo gyeouri dwaesseoyo
It's already become winter.
통증이 갑자기 사라졌어요.
tongjeung-i gapjagi sarajeosseoyo
The pain suddenly disappeared.
In every one, the English translation is also active-looking — "a problem came up," "the money ran out," "an idea came to me," "a fire broke out." That's the key cross-linguistic point below.
Why English speakers already have the right instinct — mostly
Here's the reassuring part. English expresses these same events with active intransitive verbs, not passives: the money ran out, not the money was run out; a fire broke out, not a fire was broken out; an idea occurred to me, not an idea was occurred. So your English instinct actually matches Korean here — say the event actively, with the affected thing as the subject.
The trouble starts only after you've studied the Korean passive and become eager to use it. Learners who have just mastered 잡히다, 먹히다, 열리다 start reaching for a passive everywhere, and they mistakenly apply it to verbs that are already patient-subject. The result is double-marking: 생기다 ("arise") becomes ×생겨지다 ("be arisen"?), 나다 ("occur") becomes ×나지다. These forms stack a passive on top of a verb that is already, in effect, passive in meaning — like saying "was arisen." The cure is to recognize the unaccusative class and leave it alone: these verbs are complete as they are.
우유가 다 떨어져서 사러 가야 돼요.
uyuga da tteoreojeoseo sareo gaya dwaeyo
We're all out of milk, so I have to go buy some.
아직 시간이 조금 남았어요.
ajik sigani jogeum namasseoyo
There's still a little time left.
Why so many Korean events avoid the passive
This class also explains a broader habit of Korean that puzzles learners: Korean narrates a huge range of happenings with 나다/생기다/되다 rather than the English-style passive or an agentful active. "An accident happened" is 사고가 났어요 (unaccusative 나다), not a passive. "It worked out" is 잘 됐어요 (unaccusative 되다). Because the language has these ready-made patient-subject verbs, it reaches for them instead of constructing a passive — which is one reason Korean prefers active-looking sentences far more than English does. Getting comfortable with unaccusatives is therefore not a side-topic; it's central to sounding natural.
어젯밤에 큰 사고가 났어요.
eojetbame keun sagoga nasseoyo
A big accident happened last night.
준비가 다 됐으니까 이제 출발해요.
junbiga da dwaesseunikka ije chulbalhaeyo
Everything's ready now, so let's head out.
Common Mistakes
1. Stacking -어지다 on an unaccusative. 생기다 is already patient-subject; there is no ×생겨지다.
❌ 갑자기 문제가 생겨졌어요.
Wrong — 생기다 needs no passive; it's already a patient-subject verb.
✅ 갑자기 문제가 생겼어요.
gapjagi munjega saenggyeosseoyo
A problem suddenly came up.
2. Passivizing 나다. "A fire broke out" is 불이 났어요 — 나다 takes no passive.
❌ 불이 나졌어요.
Wrong — there is no ×나지다; use 났어요.
✅ 불이 났어요.
buri nasseoyo
A fire broke out.
3. Adding -어지다 to 되다. 되다 already means "become / get done"; ×되어지다 is a classic over-passivization.
❌ 일이 잘 되어졌어요.
Wrong — 되다 is already unaccusative; say 잘 됐어요.
✅ 일이 잘 됐어요.
iri jal dwaesseoyo
Things worked out well.
4. Using the transitive 남기다 for the intransitive "be left." 남다 (remain) is the patient-subject verb; 남기다 (leave something) needs an agent and an object.
❌ 시간이 조금 남겼어요.
Wrong — 'time is left' is intransitive: 남았어요, not the transitive 남기다.
✅ 시간이 조금 남았어요.
sigani jogeum namasseoyo
There's a little time left.
5. Marking the patient as an object. An unaccusative's affected thing is the subject (이/가), never an object (을/를).
❌ 좋은 생각을 났어요.
Wrong — 나다 is intransitive; the idea is the subject: 좋은 생각이 났어요.
✅ 좋은 생각이 났어요.
joeun saenggagi nasseoyo
A good idea came to me.
Key Takeaways
- Unaccusative verbs are intransitives whose single subject is a patient, not an agent — 되다, 생기다, 나다, 남다, 사라지다, 떨어지다.
- Because the affected thing is already the subject, there is nothing to promote and no agent to demote, so these verbs cannot be passivized: ×생겨지다, ×나지다, ×되어지다 are all errors.
- Your English instinct matches Korean — "the money ran out," "a fire broke out" — so state these events actively; the danger is over-applying the passive after you've learned it.
- Korean narrates many events with these ready-made verbs (사고가 나다, 잘 되다) instead of a passive, which is why they're central to sounding natural.
- Keep the patient in the subject slot (이/가), and don't confuse an unaccusative with its transitive lookalike (남다 vs 남기다).
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Start learning Korean→Related Topics
- Transitive/Intransitive Verb Pairs (열다/열리다, 붙다/붙이다)TOPIK 3 — Korean rarely uses one verb for both 'X happens' and 'someone does X' — instead it has paired verbs, one intransitive and one transitive, built from the same 이/히/리/기/우 machinery as causatives and passives; this is the everyday, high-frequency face of the whole voice system.
- Lexical vs Derived Verb PairsTOPIK 3 — Not every intransitive/transitive pair is a tidy suffix derivation — some are suppletive (two unrelated roots like 넣다/들어가다), and a few are single labile verbs (움직이다) that never change form; assuming a clean 이/히/리/기 pattern everywhere is a reliable way to coin verbs that don't exist.
- The 되다 Passive: N이/가 되다, N하다 → N되다TOPIK 2 — 되다 is the light-verb passive that partners Sino-Korean action nouns and the huge N하다 verb class: swap 하다 → 되다 to get 'be/get X-ed' — 사용하다 → 사용되다 'be used', 시작하다 → 시작되다 'begin'. It's the passive escape hatch for the thousands of 하다-verbs that have no fused suffix passive.
- Why Korean Uses the Passive Far Less Than EnglishTOPIK 3 — Korean strongly prefers active and topic-fronted sentences where English reaches for the passive: 은/는 topic-marking plus free subject-dropping let the patient come first while the verb stays active — so 'this book was written by a famous author' is naturally 이 책은 유명한 작가가 썼어요, not a be-passive.