kare ha bouryoku wo tukawanakatta.

は marks the topic of the sentence.

So 彼は暴力を使わなかった means something like:

• As for him, he did not use violence
• He did not use violence

In English, we usually just say he, but in Japanese, は often sets up what the sentence is about.

A very important point: は is written ha but pronounced wa here.

を marks the direct object of the verb—the thing being used, eaten, seen, etc.

Here:

• 暴力 = violence
• を使う = to use something

So 暴力を使う literally means to use violence.

This is very standard Japanese grammar:

• 道具を使う = use a tool
• 日本語を使う = use Japanese
• 暴力を使う = use violence

使わなかった is the plain past negative form of 使う.

Breakdown:

• 使う = to use
• 使わない = do not use
• 使わなかった = did not use

So the sentence is in casual/plain style, not polite style.

The polite version would be:

• 彼は暴力を使いませんでした。

Great question. Verbs ending in う are a special case in the negative.

For most godan verbs, you change the final sound to the a-row before adding ない. But when the verb ends in う, it changes to わ, not あ.

So:

• 使う → 使わない
• not 使あない

Other examples:

• 会う → 会わない
• 言う → 言わない
• 買う → 買わない

This is just a standard conjugation pattern you need to memorize.

The dictionary form is 使う (つかう), meaning to use.

From that form, you get:

• 使う = use / will use
• 使わない = do not use
• 使った = used
• 使わなかった = did not use

So if you look up this verb in a dictionary, search for 使う.

Both are possible, but they do slightly different things.

• 彼は暴力を使わなかった。
  = As for him, he did not use violence.
  This sounds like a neutral statement about him.

• 彼が暴力を使わなかった。
  = He was the one who did not use violence.
  This can sound more focused or contrastive, depending on context.

Very roughly:

• は = topic / contrast / general statement
• が = subject focus / identifying who did it

In many beginner sentences, は is used because it is the most natural way to present the topic.

Yes, very often.

Japanese frequently leaves out subjects and topics when they are already understood from context. So in a real conversation, you might simply hear:

• 暴力を使わなかった。

and the listener would understand who is being talked about from context.

Adding 彼は makes the sentence clearer in isolation, which is why it often appears in textbooks or examples.

Yes, it is natural and understandable. It means to use violence.

That said, Japanese also often uses expressions like:

• 暴力を振るう = to commit violence / to resort to violence
• 暴力に訴える = to resort to violence

So 暴力を使う is fine, but depending on the context, another expression may sound more idiomatic or more specific.

Still, for learning basic grammar, 暴力を使う is completely useful and clear.

By itself, it usually means he did not use violence in the relevant past situation being discussed.

The plain past negative does not automatically mean never in his life. It depends on context.

For example:

• In a story about one argument, it means he did not use violence then.
• In a broader discussion of his behavior, it could mean he was the kind of person who did not use violence, but that broader meaning comes from context.

Japanese often relies on context more than English does.

Changing を to は often adds contrast.

• 暴力を使わなかった。
  = He did not use violence.

• 暴力は使わなかった。
  = He did not use violence, though maybe he did something else.

So は can imply something like:

• he did not use violence, but
• perhaps he used threats, persuasion, pressure, or something else

This contrast may be subtle, but it is a very common effect of は.

It is plain/casual style because the verb ends in 使わなかった.

That does not always mean it is rude. Plain style is used in many situations, including:

• casual conversation
• narration
• written prose
• talking to close friends or family
• internal thoughts

If you want a polite version, use:

• 彼は暴力を使いませんでした。

Same meaning, but more polite.

The readings are:

• 彼 = かれ
• は = pronounced わ
• 暴力 = ぼうりょく
• を = usually pronounced お
• 使わなかった = つかわなかった

So the whole sentence is pronounced:

かれ は ぼうりょく を つかわなかった
with は sounding like わ and を sounding like お in normal speech.

The spaces are just for learners.

Normal Japanese is usually written without spaces:

彼は暴力を使わなかった。

Learning materials often add spaces to help beginners see the parts more clearly:

• 彼
• は
• 暴力
• を
• 使わなかった

But in real Japanese writing, you normally would not write those spaces.