Conjugating Japanese Adjectives: It’s Easier Than You Think!

Adjectives are words that are used to describe things. They play a vital role in increasing your language fluency. Japanese adjectives are broadly divided into two categories: i-adjectives and na-adjectives.

I-adjectives end in -i and are conjugated similarly to verbs. Na-adjectives end in -na when they come before a noun and are conjugated using the copula -desu. In this beginner’s guide to Japanese adjectives, we’ll look at the two types of adjectives, how to conjugate them, and how to use them in conversation.


I-AdjectivesA white calendar showing the date of July 07. It is on a wooden surface, which is the same as the background.

In broad terms, i-adjectives are words of Japanese origin, usually written with one kanji character using its kun-yomi, or native Japanese reading. They are conjugated similarly to Japanese verbs and are also known as adjectival verbs.

This is an important distinction because it means that i-adjectives can be used without any additional verbs. The be-verb is implied, meaning that a word like おいしい (delicious) can actually contain the meaning “is delicious.” We’ll come back to this later.

You can easily identify i-adjectives because they end with い. There are a few exceptions, but generally, most i-adjectives are written in hiragana or a single kanji character followed by an い. Here are some of the most common and familiar i-adjectives.

  1. *Cute:   可愛い (かわいい – kawaii)
  2. *Delicious:   美味しい (おいしい – oishii)
  3. Fun 楽しい たのしい tanoshii
  4. *Interesting:  面白い (おもしろい – omoshiroi)
  5. Hot:  暑い (あつい – atsui)
  6. Cold:  寒い (さむい – samui)
  7. Big:  大きい (おおきい – ookii)
  8. Small:  小さい (ちいさい – chiisai)

*Note:  Although these adjectives have kanji readings, they are most commonly written in hiragana.

You can use i-adjectives either before a noun or at the end of a sentence. Here are some examples:

  1. おいしいパン Oishii pan Delicious bread
  2. このパンはおいしいです。Kono pan wa oishii desu. This bread is delicious.

In the second example, the i-adjective is used before -desu. This is the polite form. The -desu is not used in the casual form. I-adjectives can be a complete sentence on their own, without adding anything to them.


Na-AdjectivesAn illustration of a pink circle in the middle, with sakura flowers drawn inside of it. The background is white, which makes it resemble the flag of Japan, but pink. The title "Japnaese Na-Adjectives" is written in the center.

Na-adjectives are mostly words of Chinese origin, written as a compound of 2 kanji characters and read with the on-yomi, or the reading that was derived from Chinese pronunciation.

They end in -na when used directly before a noun. Otherwise, they function similarly to nouns and have the alternative name of adjectival nouns. They are conjugated using the copula -desu.

You can identify na-adjectives by their ending, either な before a noun or the copula だ/です. Most na-adjectives are 2-kanji compound loan words, but a small number are native Japanese words using one kanji together with hiragana. Here are some of the most common and familiar na-adjectives.

  1. Well, energetic:   元気 (げんき – genki)
  2. *Clean/pretty:   きれい/奇麗 (きれい – kirei)
  3. Famous:  有名 (ゆうめい – yuumei)
  4. Handy:  便利 (べんり – benri)
  5. Important:  大切 (たいせつ – taisetsu)
  6. Like:  好き (すき – suki)
  7. Dislike:  嫌い (きらい – kirai)

*Note:   Although both meanings of the word have the same kanji, generally “clean” is written きれい/キレイ, while “pretty” is written 綺麗.


Na-Adjectives That End in “い

Confusingly, a few na-adjectives, like kirei and kirai, also end in “い.” So how can you tell them apart?

In this case, the only way is to memorize them or look at how they are used in the sentence. Na-adjectives must be followed by な or a form of だ/です. Although they might be used on their own in a very casual or slang context, this is not grammatically correct.

な is used before nouns, and だ/です is used at the end of a sentence.

Here are some examples:

  1. 元気なこども Genki na kodomo An energetic child
  2. あの子供は元気だ。Ano kodomo wa genki da. That child is energetic.

Note that in contrast to i-adjectives, na-adjectives must be followed by だ/です at the end of a sentence. The way to make a polite sentence form is to use です rather than だ.

Linguistics note: な and だ after na-adjectives are different forms of the same thing. They are derived from classical Japanese forms but have the same root, and if you keep this in mind, it will help you remember that na-adjectives need to be followed by one or the other, depending on where they come in the sentence.


Conjugation of I-AdjectivesA bunch of dried bamboo lined up next to one another. The title "Conjugating Japanese I - Adjectives" is written in the middle in white, on a black transparent rectangle.

I-adjective conjugation is broadly similar to verb conjugation. Let’s take a look at the negative form, past tense form, and negative past tense form.


1.  I-Adjective Negative Form

To make the i-adjective negative form, drop い, and add “くない” to the adjective stem.

  • 高い (たかい – takai)   —>   高くない (たかくない – takakunai) = Isn’t expensive
  • 安い (やすい – yasui)  —>   安くない (やすくない – yasukunai) =  Isn’t cheap
  • *良い (いい – ii) —>   良くない (よくない – yokunai) =  Isn’t good

*Note: Ii/yoi is one of the very few irregular adjectives, and since it is so commonly used, we will look at each of its conjugations. To sum it up briefly, the positive present tense “ii” is used mainly when speaking, while “yoi” is more common in writing, and is considered more formal. Yoi is derived from the older adjective yoshi (same kanji), and over time “yoi” became “ii” in speech because it is easier to say. In the Kansai region, you may hear it pronounced as “ええ (ee).”

Let’s look at some sample sentences for the negative form.

  1. あのレストランは高くない。 (Ano resutoran wa takakunai)  –  That restaurant isn’t expensive.
  2. この服は安くない。 (Kono fuku wa yasukunai) – These clothes aren’t cheap.
  3. 彼の態度はよくない。 (Kare no taido wa yokunai)  –  His attitude isn’t good.


2.  I-Adjective Past Tense Form

To make the i-adjective negative form, drop “い,” and add “かった” to the adjective stem.

  • 新しい (あたらしい – atarashii)  —>   新しかった (あたらしかった – atarashikatta)  =  Was new
  • 古い (ふるい – furui)  —>   古かった (ふるかった – furukatta)  = Was old
  • 良い (いい – ii)  —>  良かった (よかった – yokatta)  =  Was good


Let’s look at some sample sentences for the past tense form.

  1. 彼女の車は新しかった。(Kanojo no kuruma wa atarashikatta)  –  Her car was new.
  2. おじいさんの家は古かった。 (Ojiisan no ie wa furukatta)  –  My grandfather’s house was old.
  3. あの映画はよかった。 (Ano eiga wa yokatta)  –  That movie was good.


Special I-Adjective:  良い(Ii/Yoi)

Yokatta is a versatile expression, and in addition to the meaning shown above, it can also be used to express relief or joy about something that happened.

Here is an example:

John:  事故にあったけど、けがはなかった。 I had an accident, but I wasn’t injured.

Rachel:  無事でよかった! I’m so glad you’re okay!


3.  I-Adjective Negative Past Tense Form

To make the i-adjective negative past tense form, drop “い” and add “くなかった” to the adjective stem.

  • 難しい (むずかしい – muzukashii)  —>   難しくなった (むずかしくなかった – muzukashikunakatta)  =  Wasn’t difficult
  • 優しい (やさしい – yasashii)  —>  優しくなかった (やさしくなかった – yasashikunakatta)  =  Wasn’t kind
  • 良い (いい – ii)  —>  良くなかった (よくなかった – yokunakatta)  =  Wasn’t good


Let’s look at some sample sentences for the negative past tense form:

さっきのテストは難しくなかった。 (Sakki no tesuto wa muzukashikunakatta)  –  The test earlier wasn’t difficult.

一年生の時の先生は優しくなかった。 (Ichinensei no toki no sensei wa yasashikunakatta)  –  My first-grade teacher wasn’t kind.

昨日は気分がよくなかった。 (Kinou wa kibun ga yokunakatta)  –  I didn’t feel well yesterday.


Polite Form:  I-Adjective Negative Past Tense Adjectives

The only change needed to make i-adjectives polite form is to add です to the end of the sentence. You don’t need to change or add anything else.

彼の態度はよくないです。 (Kare no taido wa yokunai desu)  –  His attitude isn’t good.

彼女の車は新しかったです。(Kanojo no kuruma wa atarashikatta desu)  –  Her car was new.

さっきのテストは難しくなかったです。 (Sakki no tesuto wa muzukashikunakatta desu)  –   The test earlier wasn’t difficult.

Next, let’s look at the conjugations for na-adjectives.


Conjugation of Na-AdjectivesAn illustration of pink sakura cherry trees on the bottom with a pink background. Some white leaves are seen floating in the sky. The title "Conjugating Japanese Na-Adjectives" is written in black at the top of the illustration.

Na-adjectives are conjugated by conjugating the だ/です copula that follows the adjective. You may have studied this when learning to construct basic sentences, and if so, you will find it works the same way here.

We will practice the negative, past tense, and negative past tense forms. Note that “だ” is the casual form, and “です” is the polite form, which is true for all forms.


1.  Na-Adjective Negative Form

To make the na-adjective negative form, change だ to じゃない, and change です to ではない.

  • 安全だ (あんぜんだ – anzen da)   —>   安全じゃない (あんぜんじゃない – anzen janai)  =  Isn’t safe
  • 簡単です (かんたんです – kantan desu)  —>   簡単ではない (かんたんではない – kantan dewa nai)  =  Isn’t easy


Let’s look at some sample sentences for the negative form:

  1. あの船は安全じゃない。(Ano fune wa anzen janai)  –  That boat isn’t safe.
  2. この問題は簡単ではない。 (Kono mondai wa kantan dewa nai)  –  This problem isn’t easy.


2.  Na-Adjective Past Tense Form

To make the na-adjective past tense form, change “だ” to “だった,” or change “です” to “でした.”

大変だ (たいへんだ – taihen da)  —>  大変だった (たいへんだった – taihen datta)  =  Was tough/difficult

必要です (ひつようです – hitsuyou desu)  —>  必要でした (ひつようでした – hitsuyou deshita)  =  Was necessary

Let’s look at some sample sentences for the past tense form:

  1. その経験は大変だった。 (Sono keiken wa taihen datta)  –  That experience was tough.
  2. あなたのお手伝いは必要でした。 (Anata no otetsudai wa hitsuyou deshita)  –  Your help was necessary.


3.  Na-Adjective Negative Past Tense Form

To make the na-adjective negative past tense form, change “だ” to “じゃなかった” and change “です to ではなかった.”

  • 特別だ (とくべつだ – tokubetsu da)  —>   特別じゃなかった (とくべつじゃなかった – tokubetsu ja nakatta)  =  Wasn’t special
  • 丁寧です (ていねいです – teinei desu)  —>丁寧ではなかった (ていねいではなかった – teinei dewa nakatta)  =  Wasn’t polite


Let’s look at some sample sentences for the negative past tense form.

  1. あのケーキは特別じゃなかった。 (Ano keeki wa tokubetsu ja nakatta)  –  That cake wasn’t special.
  2. 彼の対応は丁寧ではかなった。 (Kare no taiou wa teinei dewa nakatta)  –  His response wasn’t polite.


Polite Form:  Na-Adjective Past & Negative Past Tense

The na-adjective forms can be made more polite by changing “ない” to “ありません,” like this:

  • じゃない janai → じゃありません ja arimasen
  • ではない dewa nai → ではありません dewa arimasen>
  • じゃなかった ja nakatta → じゃありませんでした ja arimasen deshita>
  • でわなかった dewa nakatta → ではありませんでした dewa arimasen deshita>

By now, you have mastered the basics of Japanese adjectives. Now you can describe things in a variety of ways. Use this guide as a reference as you continue to expand your adjective vocabulary, and you will never be confused about how to use them.

Be sure to check out more of our free learning Japanese lessons.  Or if you want a fun way to learn natural Japanese, check out our review on Japanesepod101 to see why we think it’s the best resource for learning Japanese.  Happy studying!


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