How to Form Negative Sentences in Japanese① Nouns, na-Adjectives, and i-Adjectives

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How to Make Negative Sentences in Japanese

In this article, you will learn how to make negative sentences in Japanese step by step. This beginner-friendly guide explains Japanese negative forms clearly by part of speech.

What You Will Learn in This Lesson

In this lesson, we focus on negative forms for:

  • nouns(名詞)
  • na-adjectives(ナ形容詞)
  • i-adjectives(イ形容詞)

The order matters. We learn negative forms in the easiest and most logical order, starting with simpler patterns.

Negative forms for verbs are explained in a separate article, as they involve more patterns and sound changes.
👉 How to Form Negative Sentences in Japanese② Verbs (Group 1, 2, and 3) Beginner Guide

Quick Summary — Negative Forms by Part of Speech

Part of SpeechNegative Form (Plain)Negative Form (Polite)Example
Nouns〜じゃない〜じゃないです
〜じゃありません
〜ではありません
学生じゃないです
na-Adjectives〜じゃない〜じゃないです
〜じゃありません
〜ではありません
元気じゃないです
i-Adjectives〜くない〜くないです
〜くありません
高くないです

One Important Rule for Beginners

  • Nouns & na-adjectives use じゃない
  • i-adjectives use 〜くない
  • Verbs never use じゃない

👉 This is the most important point to remember.

Negative Form of Nouns

Nouns form the negative using:

  • 〜じゃない (plain)
  • 〜ではありません (polite)

Examples

  • 学生じゃないです。
  • 先生じゃないです。
  • 日本人ではありません。
  • 飛行機じゃありません。
  • 今日は晴れではありません。
  • これはコーヒーではありません
  • あれはりんごではありません

Why Nouns Use じゃない

Nouns do not describe actions or qualities.
They simply state what something is or is not.

In Japanese, negation for nouns is expressed by changing the copula, not the noun itself.
👉 Noun + じゃない is the basic negative pattern.

Negative Form of na-Adjectives

Na-adjectives use the same negative pattern as nouns:

  • 〜じゃない (plain)
  • 〜ではありません (polite)

Na-Adjectives Examples

  • 元気(な)→ 元気じゃないです。
  • 病気(な)→ 病気じゃないです。
  • 静か(な)→ 静かじゃないです。
  • 便利(な)→ 便利ではありません。
  • 不便(な)→ 不便ではありません。
  • 有名(な)→ 有名じゃありません。
  • 暇(な)→ 暇じゃないです。

Why Nouns and na-Adjectives Are Grouped Together

Na-adjectives behave like nouns in many grammatical structures.
They rely on the copula (だ / です) in affirmative sentences and use じゃない / ではありません in negative sentences.

Because of this shared behavior, nouns and na-adjectives are taught together.

Common Beginner Mistake

❌ 元気くないです
⭕ 元気じゃないです

Why this happens:
Learners overapply the 〜くない rule from i-adjectives.

How to avoid it:
Na-adjectives use じゃない, not くない.

Negative Form of i-Adjectives

I-adjectives form the negative by changing:

  • い → くない

I-Adjectives Examples

  • 高い→ 高くないです。
  • 安い→ 安くないです。
  • 忙しい→ 忙しくないです。
  • 美味しい→ 美味しくないです。
  • 不味い→ 不味くないです。
  • 優しい→ 優しくないです。
  • 冷たい→ 冷たくないです。

Why い Changes to く

The final い changes to く to connect smoothly to the negative ending ない.
This is a grammatical change unique to i-adjectives.

I-adjectives express negation by changing their own form,
not by adding じゃない.

Difference from Nouns / na-Adjectives

  • Nouns → じゃない
  • na-adjectives → じゃない
  • i-adjectives → くない

I-adjectives never use じゃない.

Common Beginner Mistakes (More often)

This is one of the most common mistakes beginners make when learning Japanese negative forms.
This mistake occurs even more frequently than common mistakes with na-adjectives.

❌ 優しいじゃないです
⭕ 優しくないです

❌ 可愛いじゃないです
⭕ 可愛くないです

❌ 辛いじゃないです
⭕ 辛くないです

Why this happens:
Learners treat じゃない as a general negative form.

How to avoid it:
If an adjective ends in , the negative form must be 〜くない.

Quick Summary for Beginners

Use this rule to choose the correct negative form:

  • Nouns → じゃない / ではありません
  • na-adjectives → じゃない / ではありません
  • i-adjectives → 〜くない / 〜くないです

Negative Form vs Lexical Negatives

Japanese sometimes has two ways to express a negative meaning:

  • Grammatical negation (〜じゃない / 〜くない)
  • A separate word with a negative meaning (嫌い, 不味い, etc.)

These are not the same.

na-Adjective Example

  • お刺身は好きじゃないです。
    → Neutral, soft
    → “I don’t like sashimi.”
  • お刺身は嫌いです。
    → Stronger, emotional
    → “I dislike sashimi.”

Using じゃない often sounds less strong and more polite.

i-Adjective Example

  • このお寿司は美味しくないです。
    → Mild, objective evaluation
    → “This sushi isn’t very good.”
  • このお寿司は不味いです。
    → Very strong and direct
    → “This sushi is bad.”

👉 Negative forms soften meaning, while lexical negatives express stronger judgment.

What Comes Next — Using Negative Forms in Sentences

Connecting Negative Forms with から / ので / が / けど

Connecting Negative Forms with から / ので / が / けど by Part of Speech.

Part of SpeechNegative FormConnectorExample Sentence
Nouns〜じゃないから / ので学生じゃないから、割引は使えません。Because I’m not a student, I can’t use the discount.
〜じゃないが / けど日本人じゃないけど、日本語は話せます。I’m not Japanese, but I can speak Japanese.
na-Adjectives〜じゃないから / ので体調がよくないから、今日は休みます。
I’m not feeling well, so I’m taking the day off.
〜じゃないが / けど静かじゃないけど、便利な場所です。It’s not quiet, but it’s a convenient area.
i-Adjectives〜くないから / ので高くないから、これを買います。Because it’s not expensive, I’ll buy this one.
〜くないが / けど買い物に行きたいけど、今日は疲れてるから家でゆっくりします。
I want to go shopping, but I’m tired today, so I’ll relax at home.

Final Summary

In this lesson, you learned how to form negative sentences in Japanese for three parts of speech:

  • Nouns → 〜じゃない / 〜ではありません
  • na-adjectives → 〜じゃない / 〜ではありません
  • i-adjectives → 〜くない / 〜くないです

The key point is that Japanese negative forms are determined by part of speech.
You cannot freely mix patterns, and using the correct form from the beginning helps you avoid many common beginner mistakes.

You also learned how negative forms can sound soft or strong,
and how to connect them with expressions like から, ので, が, and けど.

What Comes Next: Negative Forms of Verbs

In the next article, we will focus on verb negative forms.

Verb negatives are more complex because:

  • the form changes depending on the verb group
  • there are sound changes
  • learners often overuse じゃない with verbs

In the next lesson, you will learn:

  • how to form verb negatives step by step
  • the difference between Group 1, Group 2, and Group 3 verbs
  • why mistakes like 食べるじゃない happen, and how to fix them

👉 Next article: How to Form Negative Sentences in Japanese: Verbs (Group 1, 2, and 3)

あわせて読みたい
How to Form Negative Sentences in Japanese② Verbs (Group 1, 2, and 3)Beginner Guide A beginner-friendly guide to Japanese verb negatives. Learn how to form negative verbs by Group 3, 2, and 1, and how to use them naturally in sentences with から / ので / が / けど.

Thanks for reading!
My one-on-one online lessons are relaxed and flexible—no pressure, mistakes are part of learning.
LessonInstagram | Threads

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