The sentence-ender のだ[noda], or the more casual んだ[nda], is often used to end sentences that comment on something someone else just said or something else that just became relevant in the surrounding environment. It commonly marks explanations, rephrasings, critiques, or discoveries, but it can also mark other sorts of sentences.
今日から学校が始まる。休みは終わったのだ。
Kyō kara gakkō ga hajimaru. Yasumi wa owatta noda.
School starts today. (It means that) the break is over.
あ、事故があったんだ。
A, jiko ga atta nda.
Oh, there was an accident.
This ending is common in Japanese, but it’s so contextual that it can be quite tricky for learners to master. In this post, we’ll give you some hints on how to best get started with using this ending, and we’ll warn you about some situations where you should not use it, as it might be considered rude.
Ready to go? Let's dive in!
のだ[noda], and its various forms, always come at the end of a sentence. のだ[noda] follows the plain form of a verb, adjective, or noun + だ[da].
Plain Form
verb, adjective, noun + だ[da]
のだ
noda
ごめん、今日は 忙しいんだ。
Gomen, kyō wa isogashii nda.
Sorry, I’m busy today.
When the だ[da] that would usually follow a noun or na-adjective is used before のだ[noda], it becomes な[na] instead.
このパソコン、すごく便利なんです。
Kono pasokon, sugoku benri na ndesu.
This computer is very convenient.
The colloquial version of のだ[noda] is んだ[nda], but female speakers will often use の[no] as the informal version instead. You can also create more polite versions of のだ[noda] by using the formal forms of だ[da].
Formality | Plain form | Polite form |
|---|---|---|
Colloquial | んだ[nda] / の[no] | んです[ndesu] |
Formal | のだ[noda] | のです[nodesu] |
Formal | のである[nodearu] |
Because のだ[noda] is most often used in conversations, you will probably hear the colloquial んだ[nda] or の[no] most frequently.
When のだ[noda] is used in a question, it still comes toward the end, but it is most often followed by the question marker か[ka]. However, keep in mind these two special cases:
In colloquial forms, a rising intonation is used instead of か[ka].
When it is used before か[ka], the だ[da] portion of のだ[noda] is omitted.
Here’s how that will look at the end of a question:
Formality | Plain Form | Polite Form |
|---|---|---|
Colloquial | んだ(い)[nda i]? | んですか[ndesu ka] |
Formal | のか[no ka] | のですか[nodesu ka] |
Here are some examples:
明日出かけるの？
Ashita dekakeru no?
Are you going out tomorrow?
あ、どこか行くんですか。
A, dokoka iku ndesu ka?
Oh, are you going somewhere?
The main role of のだ[noda] is to indicate that the information you’re providing is a reaction to the context. This explanation might sound a bit vague, and it’s true that mastering this ending will probably require you to listen and practice, but we can still give you some starting instructions! Let’s look at some examples of contexts where you’re likely to use のだ[noda]!
Ending a sentence with のだ[noda] can indicate that you are trying to explain a previous sentence or the surrounding situation. In this use, you can think of it as meaning something like “The reason is that…” or “The fact is that…” or “It’s that…”
すみません、今日はクラスを休みます。風邪を引いたんです。
Sumimasen, kyō wa kurasu o yasumimasu. Kaze o hiita ndesu.
I’m sorry, I'm going to miss class today. (The reason is that) I caught a cold.
Depending on how certain the speaker’s explanation is, additional expressions of uncertainty like だろう[darō], かもしれない[ kamoshirenai], or に違いない[ni chigainai] can be added after のだ. When のだ is combined with these expressions, though you need to delete だ[da] and just keep の[no].
あ、事故があったのかもしれない。
A, jiko ga atta no kamoshirenai.
Oh, there might have been an accident.
のだ[noda] can be used at the end of a sentence that paraphrases, summarizes, rephrases, or reframes an earlier sentence. This use is often seen in writing.
今日から学校が始まる。休みは終わったのだ。
Kyō kara gakkō ga hajimaru. Yasumi wa owatta noda.
School starts today. (It means that) the break is over.
You’ll often use のだ[noda] to indicate you’ve just discovered something.
最近のロボットはこんなこともできるんだ。
Saikin no robotto wa kon’na koto mo dekiru nda.
(I didn’t know) recent robots can do things like this.
The difference between sentences with and without のだ[noda] is critical, especially when のだ is used with verbs related to perception, such as 見える[mieru](to be visible) and 聞こえる[kikoeru](to be audible). Let’s compare the following examples.
わあ、海が見える。
Wā, umi ga mieru.
Wow, we can see the ocean!
わあ、海が見えるんだ。
Wā, umi ga mieru nda.
Wow, (it turns out) we can see the ocean!
Usually, if you mark a discovery with のだ[noda] it implies that there has been some “lead-up” to the discovery. You don’t generally use のだ[noda] if you discover something “out of nowhere”, or just by chance.
わあ、本がたくさんある。
Wā, hon ga takusan aru.
Wow, there are a lot of books.
You can use the past tense before のだ[noda] when you discover something you should have known earlier.
ああ、ここにあったんだ。
Ā, koko ni atta nda.
(I should have realized earlier that) it was here.
It can also be used when you’ve just discovered the reason for something you previously observed.
あ、事故があったんだ。
A, jiko ga atta nda.
Oh, there was an accident.
You can use のだ[noda] to mark something you’ve just remembered or that you’ve rediscovered. In this case, though, you’ll often use the past tense: のだった[nodatta].
今日は雨が降るんだった。
Kyō wa ame ga furu ndatta.
(Oh right…) today, it was going to rain.
It can be used to express regret, when you discover that you should have done something while you had the chance.
はあ…雨が降り出す前に会社を出るんだった。
Hā... ame ga furidasu mae ni kaisha o deru ndatta.
(Sigh)…I should have left the office before it started raining.
Sometimes のだ[noda] marks background information that is necessary for you to understand the main point. In this case, the main point usually follows のだ[noda]. There are two patterns for this use:
Background
のだ
noda
Main Point
困っているんです。 助けてください。
Komatte iru ndesu. Tasukete kudasai.
I’m in trouble. Please help (me).
Background
のだ
noda
が
ga
Main Point
今日買い物に行くんですが、一緒に行きませんか。
Kyō kaimono ni iku ndesu ga, issho ni ikimasen ka?
I’m going shopping today. Do you want to go together?
のだ[noda] isn’t necessary when the listener should already know the background information. When the listener actually knows it, のだ[noda] doesn't fit!
✅田中さんは英語が上手ですが、どうやって勉強したんですか。
Tanaka-san wa eigo ga jōzu desu ga, dō yatte benkyō shita ndesu ka?
Mr. Tanaka, you’re good at English. How did you study?
❌田中さんは英語が上手なんですが、どうやって勉強したんですか。
Tanaka-san wa eigo ga jōzu na ndesu ga, dō yatte benkyō shita ndesu ka?
Using のだ[noda] often carries an implication that you and your listener see things the same way. This means that it’s often used when you want to build rapport with the listener. You’ll often use this marker in storytelling, to draw listeners in. It’s a little like you might use “you know,” in a story in English, even when the person listening to the story doesn’t actually know what you’re talking about.
昨日買い物に行ったんです。そこで、山田さんに偶然会ったんです。
Kinō kaimono ni itta ndesu. Soko de, Yamada-san ni gūzen atta ndesu.
You know, I went shopping yesterday. I bumped into Ms. Yamada there.
In certain cases, のだ[noda] can mark a command. When のだ[noda] describes an action the listener takes, it conveys what the listener should do in the situation.
早く逃げるんだ！
Hayaku nigeru nda!
You should run away immediately!
When のだ[noda] marks a fact that has already been shared with the listener, it can be used as a reminder of something they already know.
Most often, this sounds a bit reproachful, suggesting that the listener should have known or remembered. You’ll often hear it before から[kara](because).
お金がないんだから、無駄遣いしないで。
Okane ga nai nda kara, mudazukai shinaide.
Since we don’t have money (as you already know), don't waste it.
In certain situations, though, the reminder can be used in a positive manner, to encourage the listener.
あんなに一生懸命勉強したんだよ。明日の試験は、きっと大丈夫！
An’na ni isshōkenmei benkyō shita nda yo. Ashita no shiken wa, kitto daijōbu.
You've put in so much effort studying like that (as you already know). Tomorrow's exam will surely go well!
You can add のだ[noda] to a yes-no question to ask someone to confirm or explain something you and your listener both have some evidence for. Have a look at what adding のだ[noda] does to the meaning of a question:
雨が降っていますか。
Ame ga futte imasu ka?
Is it raining?
雨が降っているんですか。
Ame ga futte iru ndesu ka?
(Oh!) It’s raining?
You won’t add のだ[noda] unless you’re reacting to some evidence or context. For example, imagine you’re calling up a company, wishing to speak with a certain representative:
❌もしもし。田中部長はいらっしゃるんですか。
Moshi moshi. Tanaka buchō wa irassharu ndesu ka?
Hello. Chief Tanaka’s there?
✅もしもし。田中部長はいらっしゃいますか。
Moshi moshi. Tanaka buchō wa irasshaimasu ka?
Hello. Is Chief Tanaka there?
Sometimes using のだ[noda] at the end of a question can convey doubt or skepticism since you need to check that you understood the evidence correctly. Compare:
彼は先生ですか。
Kare wa sensei desu ka.
Is he a teacher?
彼は先生なんですか。
Kare wa sensei na ndesu ka.
He’s a teacher?
You can use your voice emphasize the specific piece of information you doubt or need more explanation for.
田中さんはA社のパソコンを買ったんですか。
Tanaka-san wa A-sha no pasokon o katta ndesu ka.
Mr. Tanaka bought a computer from company A?
Often, you will add のだ[noda] to the end of a “follow-up” question, which asks for more information about what you were just told. There are two main cases where you might do this:
Responding to information with a :
When someone tells you something, and you respond with a wh-question about that information, that follow-up question will often end with のだ (noda). This signals that you’re asking that question in response specifically to what you’ve been told.
夏休みは旅行に行く予定です。
Natsuyasumi wa ryokō ni iku yotei desu.
I have plans to go on a trip during the summer vacation.
いいですね。いつごろ行くんですか。
Ii desu ne. Itsu goro iku ndesu ka.
That sounds good. When are you planning to go?
Asking for additional details:
Once you’re told a piece of information, you can ask about whether some related detail is true by adding のだ[noda] to the end of your question. For example:
田中さんは、友達と映画を見たんですか。
Tanaka-san wa, tomodachi to eiga o mita ndesu ka.
Did Tanaka watch the movie with friends?
This type of questioning is common when the details you’re looking for would be marked by particles like で[de](at, in) or と[to](with), as well as details in subordinate clauses marked by words like から[kara](because) or ために[tame ni](for the purpose of).
英語を勉強するために、アメリカに行ったんですか。
Eigo o benkyō suru tame ni, Amerika ni itta ndesu ka.
Did you go to the U.S. (in order) to study English?
In this post, we’ve covered how to use のだ[noda] in Japanese. Here are the most important points to remember:
のだ[noda] and its variants usually come at the end of a sentence, though they can be followed by a question particle.
Adding のだ[noda] to a statement indicates that the information you provide is a reaction to context. This could be because…
You’re explaining the context
You’ve used the context to discover something
You’re paraphrasing a previous sentence
You’re giving background information about your main point
You’ve just remembered something
Adding のだ[noda] to a question also indicates that you’re reacting to information. This can mean that…
You’re asking for confirmation
You’re showing skepticism or doubt
You’re asking a follow-up or requesting details
Ultimately, using のだ[noda] will feel more natural as you listen and practice with native speakers, but hopefully this post will help give you a starting point!
Ready to practice what you’ve learned? Check out our のだ[noda]exercises! Happy learning!
