In Japanese, there is no direct parallel to the English verb “to be.” To form “to be” sentences in Japanese, like “this is the library,” we instead just add a range of different endings to the predicate (whatever word that describes the subject).
昨日はクリスマスだった。
Kinō wa kurisumasu datta.
Yesterday (was) Christmas Day.
あ、それ、私のじゃないです。
A, sore, watashi no watashi no ja nai desu.
Oh, that (is) not mine.
In Japanese class, you’ll generally hear the structures above called the state-of-being. In this post, we’ll take you through how to use the state-of-being in both the polite and plain (casual) forms. We’ll also talk a little bit about how to ask questions with “to be” at each level of formality. Let’s have a look!
The predicate of a “to be” sentence can be an (e.g. “is tall”) or a (e.g. “is a teacher”). This post is focused on how to form Japanese sentences with noun predicates.
Though some adjectives (the “na-adjectives”) do use the endings we discuss below, others will use different endings entirely. If you’re interested in how to use adjectives in “to be” sentences, you might want to have a look at our introduction to Japanese adjectives instead!
The table below outlines the main endings we add to Japanese nouns used to express a state-of-being. Notice that the ending you use will depend on the tense (non-past vs. past), the politeness (polite vs. plain), and whether the sentence is positive (“is”) or negaive (“is not”).
Form | Polite | Plain / Casual | |
|---|---|---|---|
Non-past (present or future) | Affirmative | 〜です[desu] | no ending or 〜だ[da] |
Negative | 〜じゃないです[ja nai desu] …and several other variations! | 〜じゃない[ja nai] | |
Past | Affirmative | 〜でした[deshita] | 〜だった[datta] |
Negative | 〜じゃなかったです[ja nakatta desu] …and several other variations! | 〜じゃなかった[ja nakatta] | |
This is just the quick version, though! To see examples, find out about additional endings, and learn about how to ask questions, you’ll want to check out the sections below!
In the polite form, you’ll use 〜です[desu] to express “being” in the present or future and 〜でした[deshita] in the past tense.
Polite Affirmative Ending | English |
|---|---|
〜です[desu] | am, are, is |
will be | |
〜でした[deshita] | was, were |
Let’s look at some examples!
この犬はチワワです。
Kono inu wa chiwawa desu.
This dog is a Chihuahua.
母は先生でした。
Haha wa sensei deshita.
My mother was a teacher.
So far, pretty simple! But things get a bit more complicated when we look at negative sentences!
In the polite form, there are a few different ways to express a negative state-of-being in each tense. As you can see じゃ[ja] is just a contraction of では[de wa], so there are really only two basic variations in each tense.
Tense | Polite | |
|---|---|---|
Not contracted | Contracted | |
Non-past am not | 〜ではないです de wa nai desu | 〜じゃないです ja nai desu |
〜ではありません de wa arimasen | 〜じゃありません ja arimasen | |
Past was not | 〜ではなかったです de wa nakatta desu | 〜じゃありませんでした ja arimasendeshita |
〜ではありませんでした de wa arimasendeshita | 〜じゃありませんでした ja arimasendeshita | |
How do you choose between the forms? It’s a matter of formality.
The first distinction comes from whether or not you are using a contraction, since contractions are less formal. Therefore, while the forms on the right are still polite, they are a bit less formal.
You might use these forms when chatting with your boss during a lunch break, or when talking with a stranger on the street.
You’d use the forms on the left in a public speech or in a business email.
There is also a difference in the formality of the base forms. The second base form in each tense is a bit more formal.
So, in each tense, the most formal will be the form in the lower left, while the least formal will be the form in the upper right!
Let’s look at some examples! See how the level of formality impacts the choice of negative ending?
A conversation between classmates, who are yet to establish friendship:
あ、それ、私のじゃないです。
A, sore, watashi no ja nai desu.
Oh, that’s not mine.
昨日の宿題は、このページじゃなかったです。
Kinō no shukudai wa kono pēji ja nakatta desu.
Yesterday's homework was not on this page.
A sentence in an essay or a self-introduction in public:
私はもう、中学生ではありません。高校生です。
Watashi wa mō, chūgakusei de wa arimasen. Kōkōsei desu.
I am not a junior high school student anymore. I am a high school student.
大学の専攻は日本語ではありませんでした。
Daigaku no senkō wa nihongo de wa arimasen deshita.
(My) major at college wasn’t Japanese.
Watch out for this common mistake! Students often assume that, because the affirmative non-past form 〜です[desu] becomes 〜でした[deshita] in the past tense, the negative non-past forms that include with 〜です[desu] should also end in 〜でした[deshita] in the past tense, but this is not the case!
In the negative state-of-being, the ない[nai] changes into なかった[nakatta], but 〜です[desu] stays as is!
Non-past | Past | |
|---|---|---|
Affirmative | 〜です desu | 〜でした deshita |
Negative | 〜じゃないです ja nai desu | ✅ 〜じゃなかったです ja nakatta desu ❌ 〜じゃないでした ja nai deshita ❌ 〜じゃなかったでした ja nakatta deshita |
To turn a polite state-of-being sentence into a question, you can simply add the sentence-final particle か[ka].
この犬はチワワですか。
Kono inu wa chiwawa desu ka.
Is this dog a Chihuahua?
その消しゴム、田中さんのじゃないですか。
Sono keshigomu, tanaka-san no ja nai desu ka.
Isn’t that eraser yours, Tanaka?
子供の時、好きな食べ物は何でしたか。
Kodomo no toki, suki na tabemono wa nan deshita ka.
What was your favorite food as a child?
lit. As a child, your favorite food was what?
コンサートは日曜日じゃなかったですか。
Konsāto wa nichiyōbija nakatta desu ka.
Wasn’t the concert on Sunday?
In the plain form, you’ll use the ending 〜だった[datta] to express “being” in the past tense. In the non-past tense, though there are two options: you’ll sometimes use no ending, and other times use the ending 〜だ[da].
Plain Affirmative Ending | English |
|---|---|
no ending or 〜だ[da] | am, are, is |
will be | |
〜だった[datta] | was, were |
For example:
これ？シュークリーム。
Kore? Shūkurīmu.
This? (It’s) a cream puff.
昨日はクリスマスだった。
Kinō wa kurisumasu datta.
Yesterday was Christmas Day.
Let’s have a look at when you should include and not include 〜だ[da].
In the plain form of the present tense state-of-being, you usually won’t use 〜だ[da] unless you really want to sound emphatic. This is especially true if you’re talking to another person.
For example, you might have seen or heard some characters in anime and manga use 〜だ[da] when talking to others. But in real life, 〜だ[da] generally omitted in this context: including it sounds theatrical or dramatic.
Question | Anime/Manga Response | Real-world Response |
|---|---|---|
名前は？ Namae wa? What’s your name? | ジンだ。 Jin da. I’m Jin. | ジン。 Jin. I’m Jin. |
When you’re speaking to yourself, including or dropping 〜だ[da] becomes more a matter of preference.
ああ、失敗（だ）・・・。
Aa, shippai (da)…
Oh my, (it is) a failure…
あ！虫（だ）！
A! Mushi (da)!
Oh! (There is) a bug!
However, there are some grammatical contexts in which 〜だ[da] should be included, for example:
Before the sentence-ending particles よ[yo] and ね[ne]:
田中さんって、何年生？
Tanaka san tte, nannsensei?
What grade is Tanaka in?
４年生だよ。
Yonensei da yo.
He is in grade 4.
後藤先生は本当にいいお医者さんだね。
Gotō sensei wa hontō ni ii oishasan da ne.
Dr. Gotō is really a good doctor, isn’t she?
そうだね。
Sō da ne.
Indeed.
While some Japanese speakers may leave out 〜だ[da] before よ[yo] and ね[ne], doing so has becoming quite outdated. You’ll mainly hear older female speakers drop 〜だ[da] in this context.
When using a structure like 〜といいです[to ii desu] to express how you hope something will be:
✅ 明日はいい天気だといいです。
Ashita wa ii tenki da to ii desu.
I hope the weather will be nice tomorrow.
Watch out! It’s very tempting to just use 〜だ[da] for the plain ending any time you would use 〜です[desu] in the polite form. But there are a lot of differences between these two endings, especially in the negative state-of-being. Make sure to follow the tables above, and don’t think of these as “equivalent”!
Luckily the negative state-of-being forms are much simpler in the plain form than in the polite form! Just use 〜じゃない[ja nai] in the non-past tense, and 〜じゃなかった[ja nakatta] in the past tense.
Plain Negative Ending | English |
|---|---|
〜じゃない[ja nai] | am not, aren’t, isn’t |
won’t be | |
〜じゃなかった[ja nakatta] | wasn’t, weren’t |
Here are some examples:
これは青森のりんごじゃない。あまりおいしくないから。
Kore wa aomori no ringo ja nai. Amari oishikunai kara.
This is not an apple from Aomori. Because it’s not very good.
昨日はクリスマスだった。でも、仕事は休みじゃなかった。
Kinō wa kurisumasu datta. Demo, shigoto wa yasumi ja nakatta.
Yesterday was Christmas Day. But, I was not off from work.
lit. …But work was not a holiday.
When you turn a polite state-of-being sentence into a question, you should NOT add the sentence-final particle か[ka]. Instead, just use a rising intonation on the last hiragana. Compare:
Polite Form → use か[ka] | Plain Form → use intonation |
|---|---|
この犬はチワワですか。 Kono inu wa chiwawa desu ka. Is this dog a Chihuahua? | この犬はチワワ？ Kono inu wa chiwawa? Is this dog a Chihuahua? |
In the plain form, you cannot include か[ka].
✅ 昼ご飯、何だった？
Hirugohan, nan datta?
What was your lunch?
❌ 昼ご飯、何だったか？
Hirugohan, nan datta ka?
In this article, we talked about the Japanese state-of-being: how to form “to be” sentences with a noun predicate. Keep in mind this chart of endings from the top of the post!
Form | Polite | Plain / Casual | |
|---|---|---|---|
Non-past (present or future) | Affirmative | 〜です[desu] | no ending or 〜だ[da] |
Negative | 〜じゃないです[ja nai desu] …and several other variations! | 〜じゃない[ja nai] | |
Past | Affirmative | 〜でした[deshita] | 〜だった[datta] |
Negative | 〜じゃなかったです[ja nakatta desu] …and several other variations! | 〜じゃなかった[ja nakatta] | |
Also, remember these additional points:
The state-of-being endings discussed above are used when the is a noun. Adjectives follow slightly different rules.
There are several ways to form the polite negative state-of-being. All are acceptable in all grammatical contexts, but some are more formal than others.
When asking a question, add the particle か[ka] in the polite form, but use intonation in the plain form.
Now it’s time to have a look at our Japanese state-of-being exercises to test your skills! Or, if you’d rather keep learning, find out how to form “to be” sentences with adjectives from our introduction to Japanese adjectives!
