Subject Particle 이/가

In Korean, particles are attached to nouns to show their grammatical function in a sentence. The particles 이/가 are subject particles .

They mark the noun they are attached to as the subject of the sentence—the person or thing that is doing an action or being described.

Key Functions:

Attaches directly to a noun.

Identifies the subject of the predicate (verb or adjective).

Answers the question "who?" or "what?" performed the action or has the quality.

For example, in the sentence 고양이가 자요 (The cat is sleeping), 가 tells us that the cat ( 고양이 ) is the one who is sleeping.

The choice between 이 and 가 depends on whether the noun it attaches to ends in a consonant or a vowel. This is a very common rule in Korean grammar.

Rule Summary

Last Sound of Noun · Particle · Example

Consonant (받침) · 이 · 책 + 이 → 책이

Vowel (no 받침) · 가 · 의자 + 가 → 의자가

Examples with Consonants (받침 O)

사람 + 이 → 사람이 (person)

학생 + 이 → 학생이 (student)

음식 + 이 → 음식이 (food)

Examples with Vowels (받침 X)

친구 + 가 → 친구가 (friend)

나무 + 가 → 나무가 (tree)

아기 + 가 → 아기가 (baby)

The subject particle 이/가 is used in all basic types of Korean sentences.

1. With Action Verbs

The subject is the "doer" of the action.

아기가 울어요.

친구가 와요.

바람이 불어요.

2. With Descriptive Verbs (Adjectives)

The subject is what is being described.

날씨가 좋아요.

영화가 재미있어요.

가방이 무거워요.

3. With 있다 / 없다 (to exist / to not exist)

The subject is what exists or is possessed.

시간이 있어요. (There is time / I have time.)

돈이 없어요. (There is no money / I have no money.)

질문이 있어요. (There is a question / I have a question.)

While 이/가 is the basic subject particle, it carries a specific nuance compared to the topic particle 은/는 (which you'll learn about in detail later). The key role of 이/가 is often to identify or introduce something new.

1. Identifying the Subject (Emphasis)

Use 이/가 when you want to specifically point out who or what the subject is, especially when answering a "who?" ( 누가 ) or "what?" ( 뭐가 ) question.

A: 누가 전화했어요? (Who called?)

B: 민준 씨가 전화했어요. ( Minjun called.)

Here, 가 puts the focus on "Minjun" as the specific person who called.

2. Introducing New Information

When you mention something for the first time in a conversation or story, you typically use 이/가 .

옛날에 왕이 살았어요. (Once upon a time, a king lived.)

저기 버스가 와요. (Look, a bus is coming over there.)

Once the "king" or "bus" is established as the topic of conversation, you would likely switch to 은/는 in subsequent sentences.

Quick review

New information

Answering "who/what?"

Emphasizing the subject