Japanese words can be classified into parts of speech according to their properties.
There are 10 parts of speech in Japanese: verb, i-adjective, na-adjective, noun, adverb, pre-noun adjectival, conjunction, interjection, auxiliary verb and postpositional particle.
This page explains the parts of speech in Japanese.
Verb
A verb is a part of speech that expresses an action or existence.
The ending of the verb changes depending on the word that follows it and the role of the verb in the sentence.
In the basic form of the verb with the unchanged ending, the vowel of the last character is “う”.
There are two types of verbs: intransitive verb and transitive verb. A verb that doesn’t require an object is an intransitive verb. A verb that requires an object is a transitive verb.
Intransitive Verb
An intransitive verb is a verb that does not require an object. The meaning can be understood by the intransitive verb alone.
泳ぐ
走る
入る
笑う
落ちる
Transitive Verb
A transitive verb is a verb that requires an object. The object “〇〇を” is placed before the verb.
（ご飯を） 食べる
（お茶を） 飲む
（趣味を） 話す
（教科書を） 忘れる
（本を） 読む
I-adjective
An i-adjective is a part of speech that expresses a property or a state.
The ending of the i-adjective changes depending on the word that follows it and the role of the i-adjective in the sentence.
In the basic form of the i-adjective with the unchanged ending, the last character is “い”.
早い
赤い
強い
高い
長い
Na-adjective
A na-adjective is a part of speech that expresses a property or a state.
The ending of the na-adjective changes depending on the word that follows it and the role of the na-adjective in the sentence.
In the basic form of the na-adjective with the unchanged ending, the last character is “な”.
綺麗な
有名な
元気な
親切な
危険な
Noun
A noun is a part of speech that describes a person or a thing.
There are a common noun that refers to a person or a thing in general, a proper noun that refers to a specific person or a thing, a numeral that indicates the quantity or the order of people or things, a formal noun that turns a sentence into a noun, and a pronoun that refers to a person or a thing without using a common noun or a proper noun.
Common Noun
A common noun is a noun that refers to a person or a thing in general.
本
電車
学校
お母さん
仕事
Proper Noun
A proper noun is a noun that refers to a specific person or thing.
日本
富士山
佐藤先生
日本銀行
東京タワー
Numeral
A numeral is a noun that indicates the quantity or the order of people or things.
１個
２回
３人
４番
５才
Formal Noun
A formal noun is a noun that turns a sentence into a noun.
（食べる） こと
（飲む） はず
（話す） とおり
（忘れる） ため
（読む） つもり
Pronoun
A pronoun is a noun that refers to a person or a thing without using a common noun or a proper noun.
私
あなた
彼
ここ
そこ
Adverb
An adverb is a part of speech that modifies a verb, an i-adjective, a na-adjective or another adverb.
There are a stative adverb that expresses the state of an action, a degree adverb that expresses the degree of a state, and a declarative adverb that determines the predicate.
Stative Adverb
A stative adverb is an adverb that expresses the state of an action.
The Stative adverb comes before a verb.
すぐに （帰る）
ゆっくり （歩く）
はっきり （言う）
どきどき （話す）
しばらく （寝る）
Degree Adverb
A degree adverb is an adverb that expresses the degree of a state.
The degree adverb comes before a verb, an i-adjective or a na-adjective.
少し （歩く）
かなり （優しい）
だいぶ （早い）
とても （綺麗な）
ちょっと （静かな）
Declarative Adverb
A declarative adverb is an adverb that determines a predicate.
For example, the predicate of a sentence containing the declarative adverb “決して” is “◯◯しない”.
決して （話さない）
あえて （寝ない）
まるで （夢のようだ）
もし （働くなら）
必ず （勉強する）
Pre-noun Adjectival
A pre-noun adjectival is a part of speech that modifies a noun.
Adding pre-noun adjectival to a noun makes the meaning of the noun clearer.
あの （人）
この （木）
大きな （家）
あらゆる （車）
いろんな （色）
Conjunction
A conjunction is a part of speech that appears at the beginning of a sentence and connects the previous sentence with the following sentence.
The Conjunction makes the relationship between the previous sentence and the following sentence clear.
（雨が降っています。） だから （家にいます。）
（雨が降っています。） しかし （外にいきます。）
（雨が降っています。） そして （風が吹いています。）
（雨が降っています。） なぜなら （６月だからです。）
（雨が降っています。） 一方 （風は吹いていません。）
Interjection
An interjection is a part of speech that expresses a response, emotion, an appeal, a greeting, a shout, etc.
はい
えっ
あのう
おはよう
よいしょ
Auxiliary Verb
An auxiliary verb is a part of speech that goes after another word and adds meaning to the other word.
The ending of the auxiliary verb changes depending on the word that follows it and the role of the auxiliary verb in the sentence.
（話し） ません
（話し） ます
（話し） ました
（綺麗） です
（綺麗） でした
Postpositional Particle
A postpositional particle is a part of speech that goes after another word and adds meaning to the other word.
Unlike an auxiliary verb, a postpositional particle does not change at the end of the word.
（私） は
（友達） と
（お父さん） の
（お母さん） に
（先生） だけ