Learn Hardcore Japanese: heya no naka ha sizuka desu.

部屋の中は静かです
- は marks a topic.
- It’s like: “As for the inside of the room, it’s quiet.”
- Often used when 部屋の中 is already known, or when you’re contrasting:
  - 外はうるさいですが、部屋の中は静かです。
    = Outside is noisy, but inside the room is quiet.
部屋の中が静かです
- が marks the subject / focus.
- Often used when answering “what is quiet?” or introducing new information:
  - どこが静かですか。 – Where is quiet?
    部屋の中が静かです。 – The inside of the room is quiet.

So both are grammatically correct; は = topic / contrast, が = subject / focus.

What kind of word is 静か? Is it a verb, an adjective, or something else?

静か (しずか) is a na-adjective (形容動詞) in Japanese.

Japanese has two main types of adjectives:

i-adjectives (end in 〜い in dictionary form)
- Examples: 大きい (big), 新しい (new), 高い (tall/expensive)
- Used like: 大きい部屋, 部屋は大きいです.
na-adjectives (do not end in 〜い in the same way)
- Examples: 静か, きれい, 有名, 便利
- Before a noun they take な:
  - 静かな部屋 = a quiet room
  - 有名な人 = a famous person
- At the end of a sentence they take だ / です:
  - 部屋は静かです。
  - この町は便利だ。

So in 部屋の中は静かです, 静か is a na-adjective describing the state of the room’s inside.

Why is it 静かです and not 静かなです or just 静か?

For na-adjectives:

Before a noun: 静かな部屋 – a quiet room
Ending a sentence (plain): 部屋は静かだ。 – The room is quiet.
Ending a sentence (polite): 部屋は静かです。 – The room is quiet.

So:

静かなです is incorrect.
- You don’t add な when the adjective comes before だ / です.
Just 静か at the end is usually felt incomplete in standard speech.
- You normally say 静かだ (plain) or 静かです (polite).

In this sentence, we are using polite speech, so 静かです is the correct form.

Can I say 部屋の中は静かだ instead of 静かです?

Yes.

部屋の中は静かです。 – polite
部屋の中は静かだ。 – plain / casual

They mean the same thing: “The inside of the room is quiet.”

Use です when speaking politely (to strangers, teachers, in formal writing). Use だ (or sometimes just softening it in other ways) with friends or in casual situations.

Why isn’t there a separate word for “is” in the sentence? Where is the “is”?

The “is” idea is mainly expressed by です (or だ in plain form).

Breakdown:

静か = quiet
静かです = “is quiet” (polite)
静かだ = “is quiet” (plain)

So in 部屋の中は静かです, the “is” is carried by です attached to the adjective. Japanese doesn’t use a separate stand‑alone verb like English “to be” in this pattern; it’s built into だ / です.

How should I translate 部屋の中は静かです naturally? Where is the “it”?

Natural translations include:

“It’s quiet inside the room.”
“The inside of the room is quiet.”
“It’s quiet in the room.”

Japanese often omits the subject (“it” here). Grammatically, 部屋の中 is the topic:

部屋の中は静かです。
Literally: “As for inside the room, (it) is quiet.”

English usually needs a subject like “it” or “the inside of the room”, but Japanese can leave that implicit.

Why don’t we use に or で for the location, like 部屋の中に静かです or 部屋の中で静かです?

Because 静か describes a state, not an action.

で usually marks the place where an action happens:
- 部屋で勉強します。 = I study in the room.
に often marks a destination or location where something exists / appears:
- 部屋の中に猫がいます。 = There is a cat in the room.

But 静かです is not an action like “study” or “play”; it’s a state (“be quiet”). For states, Japanese often just makes the place the topic with は:

部屋は静かです。 = The room is quiet / It’s quiet in the room.
部屋の中は静かです。 = It’s quiet inside the room.

So 部屋の中に静かです and 部屋の中で静かです are unnatural; you mark the place with は, not に / で, in this type of sentence.

Is the word order fixed? Could I say 静かです、部屋の中は?

Normal, natural word order in everyday Japanese is:

[Topic/Subject] + は / が + [Description]
→ 部屋の中は静かです。

You can move parts around for emphasis or poetic effect, but:

静かです、部屋の中は。
sounds like special emphasis, drama, or poetry / song lyrics. It’s not the neutral, textbook pattern.

For normal speech and writing, you should keep:

部屋の中は静かです。 as the standard word order.