Korean has four forms of negation for negative sentences. For ease of understanding, we’ll break them down into two ways: short-form negation and long-form negation.

First, let’s learn two forms of Korean negation equivalent to ‘don’t/isn’t.’
 

1. don’t / isn’t : 안 [an] + Verb/Adjective, Verb/Adjective + 지 않다 [ji anta]

안 [an] refers to one’s unwillingness and expresses the meaning of ‘does not ‘ or ‘is not.’ It applies more to the speaker’s intention and conscious choice.

   ① Short-form negation : 안 [an] + Verb/Adjective

The rule for putting a verb or adjective into the short negative form is very simple. Just add 안 immediately before verbs and adjectives.

– 안 + Verb

가다 [gada] → 안 가다 [an gada] (not to go)

먹다 [meokda] → 안 먹다 [an meokda] (not to eat)

사다 [sada] → 안 사다 [an sada] (not to buy)

마시다 [mashida] → 안 마시다 [an mashida] (not to drink)

– 안 + Adjective

맵다 [mepda] → 안 맵다 [an mepda] (not to be spicy)

예쁘다 [yeppeuda] → 안 예쁘다 [an yeppeuda] (not to be pretty)

싸다 [ssada] → 안 싸다 [an ssada] (not to be cheap)

크다 [keuda] → 안 크다 [an keuda] (not to be big)

* For 하다 [hada] action verbs, which consist of nouns and 하다 (to do), 안 goes between the noun and 하다.

공부하다 [gongbuhada] → 공부 안 하다 [gongbu an hada] : not to study

일하다 [ilhada] → 일 안 하다 [il an hada] : not to work

요리하다 [yo-lihada] → 요리 안 하다 [yo-li an hada] : not to cook

운동하다 [undonghada] → 운동 안 하다 [undong an hada] : not to work out

   ② Long-form negation : Verb/Adjective + 지 않다 [ji anta]

The second way to mark negation is to put –지 않다 right after verbs and adjectives. Fortunately, you can use this form with any verbs and adjectives. Just take the verb or adjective stem and attach –지 않다 [ji anta].

– Verb + 지 않다

자다 [jada] → 자지 않다 [jaji anta] not to sleep

읽다 [ikda] → 읽지 않다 [ikji anta]  not to read

하다 [hada] → 하지 않다 [haji anta] not to do

사용하다 [sayonghada] → 사용하지 않다 [sayonghaji anta] not to use

– Adjective + 지 않다

작다 [jakda] → 작지 않다 [jakji anta] not to be small

비싸다 [bissada] → 비싸지 않다 [bissaji anta] not to be expensive

춥다 [chupda] → 춥지 않다 [chupji anta] not to be cold

높다 [nopda] → 높지 않다 [nopjianta] not to be high

Okay, let’s move on the two forms of negation equivalent to ‘can’t.’

2. can’t : 못 [mot] + Verb, Verb + 지 못하다 [ji motada]

못 is typically used to express one’s inability. Its meaning ranges from ‘cannot’ or ‘unable to’ to ‘be impossible.’ Keep in mind that adjectives, which are also called ‘descriptive verbs’ in Korean, cannot take the negative marker with 못 / -지 못하다 in this way.

   ① Short-form negation : 못 [mot] + Verb

오다 [oda] → 못 오다 [mot oda] cannot come

하다 [hada] → 못 하다 [mot hada] cannot do

쓰다 [sseuda] → 못 쓰다 [mot sseuda] cannot write

기다리다 [gidarida] → 못 기다리다 [mot gidarida] cannot wait

   ② Long-form negation : Verb + 지 못하다 [ji motada]

뛰다 [ttwida]→ 뛰지 못하다 [ttwiji motada] cannot run

그리다 [geurida] → 그리지 못하다 [geuriji motada] cannot draw

보다 [boda] → 보지 못하다 [boji motada] cannot see

말하다 [malgada]→ 말하지 못하다 [malgaji motada] cannot speak

★ Difference in Nuance You Should Keep in Mind

It’s important to understand the slight difference in nuance between 안 / –지 않다 and  못 / –지 못하다. In English, you might say “I’m sorry I didn’t call you yesterday”ㅡand no one would be offended. However, the forms 안 / -지 않다 imply ‘choose not to’ in Korean. In other words, if you say 어제 전화 안 해서 미안해 [eoje jeonhwa an heseo mianhe] / 어제 전화 하지 않아서 미안해 [eoje jeonhwa haji anaseo mianhe] to a friend, you are saying ‘I chose not to call you yesterday.’ The better phrase is 어제 전화 못 해서 미안해 [eoje jeonhwa mot heseo mianhe] / 어제 전화 하지 못 해서 미안해. [eoje jeonhwa haji mot heseo mianhe] (I’m sorry I couldn’t call you yesterday.)

★ Proper Usage Depending on Context

Here, you’re likely to wonder what’s the difference in usage between short-form negation and long-form negation. To be brief, compared to short-form negation, long-form negation is more frequently used in formal situations and written language. So if you want to look polite, use long-form negation, even though it is a little longer!

Reference :

1. Kawasaki A. An Axiomatic Approach to Korean Grammar. Department of Physics, Massachusetts Institute of Technology. 2014.
2. Choo M, Kwak H. Using Korean.
3. Park K, Amen H, Padrón A. Korean For Beginners.