Japanese Verb Conjugation Explained

Japanese verb conjugation might seem intimidating at first, but once you understand the system, it becomes remarkably logical. Unlike English, where irregular verbs are everywhere, Japanese follows predictable patterns for the vast majority of its verbs.

The key to mastering Japanese verbs is understanding the three main categories: godan verbs (五段動詞ごだんどうし), ichidan verbs (一段動詞いちだんどうし), and irregular verbs. Each group follows its own set of rules, and learning to identify which group a verb belongs to is the first crucial step.

This guide covers how to identify each verb group, how to conjugate all three into the forms you'll use in everyday Japanese, and the specific exceptions (like 帰る and 走る) that catch most learners off guard.

Understanding the Basics

What is Conjugation?

Conjugation is the process of changing a verb's form to express different meanings like tense (past, present), politeness level, negation, and more. In Japanese, the verb different forms are made by changing the verb's ending or attaching endings to a verb stem. For godan verbs, the final mora shifts across the vowel rows; for ichidan verbs, the stem stays stable and る is removed before an ending is attached.

Key Terms You Need to Know

The Three Verb Groups

Godan Verbs (五段動詞ごだんどうし): The Five-Row Verbs

Godan verbs are called "five-row" verbs because the final mora of the verb stem can shift across five vowel rows: a, i, u, e, o. For example, 書かく changes through か, き, く, け, and こ depending on the form.

How Godan Conjugation Works

Let's use 書かく (kaku - to write) as an example. The stem is often described as kak- in romanized teaching materials, while the Japanese final mora changes across the vowel rows:

Common Godan Conjugations

Ichidan Verbs (一段動詞いちだんどうし): The Drop-る Verbs

Ichidan verbs are much simpler than godan verbs. They're called "one-row" verbs because they conjugate within a single vowel row. The rule is straightforward: drop る and add the ending.

How Ichidan Conjugation Works

Let's use 食たべる (taberu - to eat) as an example. The stem is tabe-, and it remains stable:

Comparison: Godan vs Ichidan

Notice how ichidan verbs maintain their stem (tabe) consistently, while godan verbs shift vowels throughout.

Irregular Verbs: する and 来くる

For the basic three-group system used in this guide, する and 来くる are the two major irregular verbs, along with their compounds. These are する (suru - to do) and 来くる (kuru - to come).

する (suru) Conjugations

来くる (kuru) Conjugations

How to Identify Verb Types

The most challenging part for learners is determining whether a verb is godan or ichidan, especially when it ends in る. Here's a systematic approach:

The える/いる Challenge

The trickiest verbs are those ending in える (-eru) or いる (-iru). While most are ichidan, some common ones are godan exceptions:

Conjugation Mechanics: How Endings Attach

Understanding how different forms work will help you build any conjugation you need. Let's break down the most essential forms:

Negative Form (〜ない)

Polite Form (〜ます)

Te-form (〜て)

The te-form is one of the most useful conjugations, used for requests, ongoing actions, and connecting clauses. It's also the trickiest for godan verbs because of sound changes.

Past Tense (〜た)

Good news: the past tense follows the exact same pattern as te-form, just replace て/de with た/だ:

Potential Form (can do)

Volitional Form (let's do)

Advanced: Sound Changes and 音便おんびん (Onbin)

For learners who want to understand why certain conjugations sound the way they do, this section explores the phonological patterns behind Japanese verb conjugation.

The Lost /w/ Sound

Historically, Japanese had a /w/ sound in more positions than it does today. This explains some modern conjugations:

This is why verbs ending in う don't become *あない but rather わない.

音便おんびん (Onbin): Sound Euphony

音便おんびん refers to sound changes that make words easier to pronounce. This primarily affects the te-form and past tense of godan verbs. There are three main types:

1. 促音便そくおんびん (Sokuonbin) - Gemination with っ

Verbs ending in う, つ, る become って:

• 買かう → 買かって (katte)
• 待まつ → 待まって (matte)
• 売うる → 売うって (utte)

2. 撥音便はつおんびん (Hatsuonbin) - Nasal assimilation with ん

Verbs ending in む, ぶ, ぬ become んで:

• 読よむ → 読よんで (yonde)
• 遊あそぶ → 遊あそんで (asonde)
• 死しぬ → 死しんで (shinde)

3. イ音便いおんびん (I-onbin) - Consonant deletion

Verbs ending in く, ぐ lose the consonant and add い:

• 書かく → 書かいて (kaite, from *kak-ite)
• 泳およぐ → 泳およいで (oyoide, from *oyog-ide)

Complete Conjugation Reference Charts

Godan Verb: 書かく (kaku - to write)

Ichidan Verb: 食たべる (taberu - to eat)

Irregular Verbs

Common Mistakes and How to Avoid Them

1. Misidentifying る-Ending Verbs

2. Incorrect Te-form Application

3. Forgetting 行いく Exception

4. Using ある Incorrectly

5. Confusing Potential Forms

6. Overreliance on Romaji

Practice Recommendations

Effective Drilling Strategies

1. Master Identification First

Before drilling conjugations, make sure you can correctly identify verb types. Take common verbs and practice categorizing them:

• Create flashcards with verbs on one side and their type on the other
• Use the negative test to verify godan vs ichidan
• Focus especially on える/いる exceptions

2. Learn Forms in Order of Usefulness

Don't try to learn all forms at once. Build gradually:

3. Use Verb Families

Group verbs by their ending to practice te-form and past tense patterns together:

• む group: 読よむ、飲のむ、住すむ、頼たのむ
• く group: 書かく、聞きく、歩あるく、泣なく
• す group: 話はなす、貸かす、返かえす、消けす

4. Practice in Context

Don't just drill isolated forms. Create or find sentences that use the conjugations naturally:

• 毎日まいにち日本語にほんごを勉強べんきょうします。(I study Japanese every day.)
• 昨日きのう映画えいがを見みました。(I watched a movie yesterday.)
• 本ほんを読よんで寝ねました。(I read a book and went to sleep.)

5. Use Dictionary Resources

Online dictionaries are your best friends for verification:

• Jisho.org: Shows verb type and common conjugations
• Tangorin: Includes detailed conjugation tables
• Japanese verb conjugators: Let you practice any verb in any form

Frequently Asked Questions

How do I tell if a verb ending in る is godan or ichidan?

Use this sequence when a verb ends in る:

1. If the verb does not end in る, it is godan.
2. If the sound before る is from the あ, う, or お row, it is godan.
3. If the sound before る is from the い or え row, it is usually ichidan.
4. Check for common exceptions such as 帰かえる and 走はしる, which are godan.
5. When a dictionary labels a る-ending verb as godan or ichidan, use that classification rather than relying only on the vowel test.

The negative form can also help confirm the pattern: godan verbs change their final mora to the あ row before ない, while ichidan verbs remove る and add ない.

What's the difference between verb stem and verb root?

For this guide, it is clearer to use the term verb stem rather than trying to define a separate "root." A godan verb changes its final mora across the vowel rows, while an ichidan verb keeps a stable stem and removes る before adding endings. For example, 書かく uses かき for the masu-stem, while 食たべる uses たべ. Different grammar resources use "root" and "stem" differently, so this guide avoids treating one definition as universal.

Why are する and 来くる irregular?

する and 来くる don't follow the standard conjugation patterns of godan or ichidan verbs. They have unique conjugation rules that must be memorized separately. For example, する becomes しない (not すない), and its potential form is できる (a completely different word). 来くる changes its reading between くる, こ, and き depending on the form. This includes their compounds like 勉強べんきょうする (benkyou suru) and 持もって来くる (motte kuru).

Do I need to memorize all the 音便おんびん patterns?

Not explicitly. While understanding 音便おんびん helps explain why conjugations sound the way they do, you don't need to memorize the linguistic terminology. Instead, focus on recognizing the te-form patterns: う/つ/る → って, む/ぶ/ぬ → んで, く → いて, ぐ → いで, す → して. With practice, these become automatic.

What's the fastest way to learn verb conjugation?

Start with correct verb identification, then master the most common forms first (negative, polite, past, and te-form). Use spaced repetition with flashcards, but always practice in context, creating sentences with the verbs rather than drilling isolated forms. Focus on high-frequency verbs like 食たべる, 行いく, 見みる, する, and 来くる before moving to less common ones.

Why does ある have a special negative form?

The verb ある (to exist, for inanimate objects) has one important irregularity: its plain negative is ない, not あらない. Its polite form is あります, and its past and te-forms are あった and あって. Its counterpart for animate beings, いる, conjugates regularly as an ichidan verb.