Japanese Past Tense: Complete Conjugation Guide for Beginners
Introduction: What is Past Tense in Japanese?
The past tense in Japanese indicates actions, states, or events that have already occurred. Unlike English, which often requires helper verbs like "did" or "have," Japanese expresses past tense through verb conjugation—specifically by changing the verb ending. Understanding how to use past tense in Japanese is essential for describing completed actions, sharing experiences, and narrating stories.
Japanese has two main past tense forms: the polite past (ました/でした) used in formal situations, and the plain past (た-form) used in casual speech, writing, and as a building block for more complex grammar patterns.
Formation: Japanese Past Tense Conjugation Rules
Japanese past tense conjugation follows different patterns depending on the verb type. Let's break down each category:
Polite Past Tense (ます → ました)
The polite past is straightforward—simply replace ます with ました:
| Dictionary Form | Polite Present | Polite Past | Meaning |
|---|---|---|---|
| 食べる (taberu) | 食べます | 食べました | ate |
| 行く (iku) | 行きます | 行きました | went |
| する (suru) | します | しました | did |
| 来る (kuru) | 来ます | 来ました | came |
Plain Past Tense (た-form) for Ru-Verbs (一段動詞)
For ru-verbs (ichidan verbs), drop the る and add た:
| Dictionary Form | Plain Past | Meaning |
|---|---|---|
| 食べる (taberu) | 食べた | ate |
| 見る (miru) | 見た | saw |
| 起きる (okiru) | 起きた | woke up |
Plain Past Tense (た-form) for U-Verbs (五段動詞)
U-verbs (godan verbs) follow more complex conjugation rules based on their ending consonant:
| Ending | Change | Example | Past Form |
|---|---|---|---|
| う, つ, る | → った | 買う (kau) | 買った (bought) |
| む, ぶ, ぬ | → んだ | 読む (yomu) | 読んだ (read) |
| く | → いた | 書く (kaku) | 書いた (wrote) |
| ぐ | → いだ | 泳ぐ (oyogu) | 泳いだ (swam) |
| す | → した | 話す (hanasu) | 話した (spoke) |
Exception: 行く (iku, to go) becomes 行った (itta), not 行いた.
Irregular Verbs
| Dictionary Form | Plain Past | Meaning |
|---|---|---|
| する (suru) | した | did |
| 来る (kuru) | 来た (kita) | came |
Past Tense for Adjectives and Nouns
Japanese adjectives and nouns also conjugate for past tense:
| Type | Present | Past | Polite Past |
|---|---|---|---|
| い-adjective | 高い (takai) | 高かった | 高かったです |
| な-adjective | 静かだ (shizuka da) | 静かだった | 静かでした |
| Noun + だ | 学生だ (gakusei da) | 学生だった | 学生でした |
Usage: When and How to Use Past Tense
Now that you understand how to use past tense in Japanese, here are the main contexts where you'll apply it:
- Completed actions: Describing something that finished in the past (昨日、映画を見た – I watched a movie yesterday)
- Past experiences: Talking about things you've done (日本に行ったことがある – I have been to Japan)
- Past states: Describing how things were (子供の時、この町は静かだった – When I was a child, this town was quiet)
- Sequential actions: Using て-form for the first action and た-form for the last (朝ごはんを食べて、学校に行った – I ate breakfast and went to school)
- Embedded clauses: Past tense before nouns acts like a relative clause (昨日買った本 – the book I bought yesterday)
Examples: Past Tense in Context
Here are practical example sentences demonstrating Japanese past tense conjugation in real contexts:
- 昨日、友達と東京に行きました。
Kinō, tomodachi to Tōkyō ni ikimashita.
I went to Tokyo with my friend yesterday. - その映画はとても面白かった。
Sono eiga wa totemo omoshirokatta.
That movie was very interesting. - 彼女は先週、新しい仕事を始めた。
Kanojo wa senshū, atarashii shigoto o hajimeta.
She started a new job last week. - 子供の頃、毎日サッカーをした。
Kodomo no koro, mainichi sakkā o shita.
When I was a child, I played soccer every day. - 朝ごはんを食べなかった。
Asagohan o tabenakatta.
I didn't eat breakfast. - 去年の夏は暑かったです。
Kyonen no natsu wa atsukatta desu.
Last summer was hot. - 彼は昔、医者だった。
Kare wa mukashi, isha datta.
He used to be a doctor.
Common Mistakes to Avoid
When learning Japanese past tense conjugation, watch out for these frequent errors:
- Confusing u-verb and ru-verb conjugations: Not all verbs ending in る are ru-verbs. Words like 帰る (kaeru, to return) and 走る (hashiru, to run) are actually u-verbs, so they become 帰った and 走った, not ×帰た or ×走た.
- Forgetting the 行く exception: 行く becomes 行った (itta), not ×行いた. This is the only く-ending verb with this irregular pattern.
- Mixing polite and plain forms: In a single sentence or conversation, maintain consistent formality. Don't say ×食べましたけど、行った (mixing ました and plain た).
- Incorrect い-adjective conjugation: Remove the final い before adding かった. The past of いい (good) is よかった (not ×いかった), as it derives from よい.
- Using past tense in relative clauses incorrectly: In Japanese, the verb in a relative clause should be past if the action happened before the main clause, even if English might use present tense. 昨日会った人 (the person I met yesterday) uses past tense 会った.
- Forgetting negative past forms: The negative past is formed differently: ない becomes なかった (plain) or ませんでした (polite). For い-adjectives, replace い with くなかった (高い → 高くなかった).