Embedded and Subordinate Clauses

A subordinate clause is a clause that does not stand on its own — it works as a part of a bigger clause: its subject, its object, its "because," or its noun-modifier. English marks this with a word at the front ("because it's expensive," "that he's right," "the book that I bought") and freely mixes tense and formality across the join. Japanese does the opposite on both counts, and once you see the two governing habits — the subordinator comes at the end and the inside is plain form — every embedded clause you meet becomes readable.

The subordinator comes at the end of its clause

This is the first thing to unlearn. English announces the relationship before the clause: because, when, if, that. Japanese closes the clause first and then tacks on the linker — から ("because"), とき ("when"), ば ("if"), けど ("but"), ので ("since"). The whole subordinate clause is built, and only its final particle tells you what job it was doing.

Read 高いから left to right: 高い ("expensive") lands first, then から ("because"). English puts "because" up front; Japanese puts it dead last. This is the same right-headed logic that puts the verb at the end of a sentence and the modified noun at the end of a noun phrase — see the predicate-final principle. Subordination is not a special case; it is head-finality applied to whole clauses.

Three families of subordinate clause

Every subordinate clause is doing one of three jobs. Naming them tells you which connector to reach for.

Family 1 — Complement clauses (と / こと / の)

A complement clause fills a slot that would otherwise hold a noun: the thing you think, know, or say. Because Japanese needs a noun-like unit there, the clause is wrapped — with と for quoted or reported content, and with こと or の when it is turned into an abstract "the fact/act of…." The wrapper comes, as always, at the end of the embedded clause.

Notice that inside 彼が正しいと, the subject of the little clause takes が, not は — embedded subjects are marked with が, because は sets a topic for the whole sentence, not the inner clause. The choice between こと and の is a topic of its own; see nominalization and こと vs の.

Family 2 — Adverbial clauses (から, ので, とき, ば, ても…)

These clauses answer why, when, on what condition, despite what. Each is a full clause closed off by its adverbial connector.

For the fine differences among these connectors, follow the dedicated pages — から and ので for "because," とき for "when," のに for "although." What unites them here is architecture: clause first, connector last.

Family 3 — Relative / modifying clauses (bare, before the noun)

The third family carries no connector at all. To describe a noun with a whole clause, you just place the clause — ending in its own plain predicate — directly in front of the noun. There is no relative pronoun, no "that / which / who."

The clause 私が昨日買った ("I bought yesterday") modifies 本 exactly as the adjective 赤い would modify 車 in 赤い車 — from the left, with the noun as head. This is developed in full on the relative clauses page; here it just completes the picture that all subordination in Japanese sits before what it attaches to.

The inside is plain form — even when the outside is polite

The second governing habit surprises English speakers the most: a subordinate clause takes the plain (dictionary/ない/た) form regardless of how polite the main clause is. Politeness lives on the final predicate of the sentence; the embedded clause stays plain.

In the first, 急いでください is polite, yet the reason clause is the plain 時間がない, not 時間がありません. In the second, the sentence ends in the polite 分かりませんでした, but the けど-clause holds the plain 読んだ. The politeness is applied once, at the very end.

There is one honest exception, and it is a matter of register, not grammar. The two "because" connectors から and ので can attach to a polite form when the whole utterance is deliberately formal — 〜ますから and 〜ますので are standard in service announcements and careful business speech:

But this politeness-inside is limited to から and ので. The time, condition, and concession connectors — とき, ば, ても, と, なら — take only the plain form; 行きますとき or 高いですば are simply ungrammatical. So the safe rule is: keep the inside plain unless you are consciously writing a formal 〜ますので announcement.

Watch the copula: 〜だから but 〜なので

A wrinkle that trips up nearly everyone: how a noun or a な-adjective connects to から and ので differs. With から, the plain copula だ appears (学生だから); with ので, that だ becomes な (学生なので). い-adjectives take neither — they attach bare.

There is no deep logic to memorize away here — ので historically derives from the attributive form, which is why it wants な, while から takes the plain だ. You simply learn the pair: だから / なので.

Common mistakes

Mistake 1 — Putting the connector at the front, English-style. Learners front から / とき the way English fronts "because / when."

Mistake 2 — Using polite forms inside a neutral subordinate clause. In ordinary (non-announcement) style, keeping です／ます inside reads as over-marked.

Mistake 3 — Dropping the complement wrapper と / こと / の. English "I realized he was right" has no marker, so learners omit と.

Mistake 4 — Using だ before ので. By analogy with だから, learners write 〜だので.

Mistake 5 — Marking the embedded subject with は. Inside a subordinate clause, the subject takes が, because は topicalizes the whole sentence.

Key takeaways

• A subordinate clause works as a part of a bigger clause — a complement, an adverbial, or a noun-modifier.
• The subordinator comes at the end (から, とき, ので, けど, と), never the front — subordination is right-headed like everything else in Japanese.
• Complement clauses take と / こと / の; adverbial clauses take から, ので, とき, ば, ても…; relative clauses take nothing and sit bare before their noun.
• The inside stays plain form; politeness is applied once, on the sentence's final predicate. Only から / ので admit a polite form, and only in formal register.
• Mind the copula seam: 〜だから but 〜なので, and embedded subjects take が, not は.