I have learned that in order to express must/have to in Korean, you use-(어/아/여)야 하다 and -(어/아/여)야 되다 (depending on the verb stem, you might use 어).

For example:

너는 밥을 먹어야 한다. vs 밥을 먹어야 된다. (You should have a meal)

However, I wonder if there is any difference between - 하다 and - 되다 to express the obligation.

In other usage, I hear that the former is for active while the latter for passive. But according to a similar question on other websites, it is exactly the same, though it might be a slightly different use case.

So is there any difference or is this just a synonym? My textbook doesn't distinguish them, for your information.

  • Are you asking about "해야 하다" or "아야 하다"? Please include some example sentences. You can take the examples from the link. If you have learned it, please quote the source.
    – user7
    Sep 21, 2016 at 6:48
  • If you can't transcribe what the text book says, please take a picture and post the image. Your question is even more unclear than the last one.
    – user7
    Sep 21, 2016 at 7:38
  • 1
    @Rathony No I'm asking about if there is a difference between 아야 하다 or 아야 되다. I think this question is clear enough, and doesn't have any example sentences as it is the question only about the usage of 하다 vs 되다. Maybe the link to the other question might make it confusing...
    – Blaszard
    Sep 21, 2016 at 10:47
  • @Rathony For example in DEMANDS AND OBLIGATIONS, PERMISSIONS AND PROHIBITIONS, it says A/V-아/어야 되다/하다. (must, have(to)) expresses obligation to do something or necessity in a certain situation.. But I don't understand if there is any difference between 하다 and 되다.
    – Blaszard
    Sep 21, 2016 at 10:49
  • I edited your question based on your comments. Please compare it with the original version. The reason you should have some example sentences in your question is illustrated below.
    – user7
    Sep 22, 2016 at 0:10

2 Answers 2


This is an excellent and clear question. I have had this question myself many times. Before living in Korea, I was in a 3-month intensive language training program for Korean. We were taught that the imperative form (which is the whole base of the question here) was 아/어/여 야 하다. However, when I went to Korea, I heard 아/어/여 야 되다 almost exclusively

I do not have any hard and fast grammar rule for you here, but in my experience in living in Korea for a few years and also obtaining a Korean degree in college, the verb endings

아/어/여 야 하다


아/어/여 야 되다

were used pretty much interchangeably. But they were not identical. Again, as I said, this is not a grammatical difference, but a difference in feeling or register.

아/어/여 야 하다 tends to be stronger and more imperative. It has a more emphatic feel.

아/어/여 야 되다 is weaker than the 하다 form. It is less forceful. I think that this is why it is more common; it comes across as less demanding.

I say this commonly, but a huge thing that hold up Korean learners is that they want a one to one rubric between Korean and English. They want to know exactly when to use each form. Black and White.

When to use each of these forms is more a matter of feel and less a matter of right and wrong. They are grammatically equivalent; however they show a different level of imperative necessity.

Take the example sentence as follows:

We need to go.

How do we translate this into Korean? Well, how imperative is it? Written English is somewhat deficient in this regard. The only way to know the true emphasis intended is to hear the sentence spoken.

But now look at these two sentences:

"We need to go now." versus "We need to go. Now."

The written emphasis is slightly different. The second sentence shows more imperative necessity than the first.

In my experience, the two sentences above show a good example of how to use 아/어/여 야 하다 and 아/어/여 야 되다.

Translated, the two English sentences could be written

"가야 돼요" versus "가야 해요"

The second one has a feeling of emphasis and higher necessity.

(I will leave the discussion of which 체 [register or politeness level] to be using here for another day. There are cases for both sides).

  • Thank you for the terrific answer! This is definitely a kind of answers that I wanted.
    – Blaszard
    Sep 22, 2016 at 0:25

I think you means '~을 (하지)않아야 한다.' / '~을 (하지)않아야 된다'

there is no difference with two expressions. (almost)

in this case '~한다' means 'do', '~된다' means 'be'

'신문을 보지 말아야 된다.' = 'you (or anyone) should not be reading newspaper'

'신문을 보지 말아야 한다.' = 'you (or anyone) do not read newspaper'

native Koreans doesn't distinguish them.

  • My understanding is that the difference between the forms is not the type of verb they are used with, nor that they are always used in the negative form. It is solely a matter of emphasis. The sentences in the tan box roughly capture this, although perhaps their translations are stilted.
    – Vladhagen
    Sep 21, 2016 at 20:00

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