kare no syugi ha kawarimasendesita.

Here, 彼 means he or him, and in 彼の, it becomes his.

A useful thing to know is that Japanese 彼 does not work exactly like English he in every situation. In real Japanese conversation, pronouns are often omitted if the person is already understood from context. So a full sentence like this may sound a little more explicit than natural casual speech, depending on the situation.

Also, 彼 can sometimes mean boyfriend in other contexts, but not here. In this sentence, it is simply the person whose 主義 is being talked about.

の links one noun to another. Here it shows possession or association, so:

• 彼 = he
• 彼の = his
• 彼の主義 = his principles / his beliefs / his ideology

So の is functioning a lot like the English possessive 's or of.

You can think of the basic pattern as:

• A の B = B of A / A's B

Examples:

• 私の本 = my book
• 先生の車 = the teacher's car
• 彼の主義 = his principles

主義 often refers to a person's principles, beliefs, creed, ideology, or way of thinking.

Its exact translation depends on context. It can be used for:

• personal principles
• political ideology
• a doctrine or -ism
• a strongly held policy or stance

In this sentence, it most naturally means something like:

• his principles
• his beliefs
• his ideology

So it sounds more serious and abstract than a word like 考え, which is just thoughts or ideas.

は marks the topic of the sentence.

So 彼の主義は means something like:

• As for his principles, ...
• His principles, ...

Then the sentence says what is true about that topic:

• 変わりませんでした = did not change

So the full structure is:

• 彼の主義は = as for his principles
• 変わりませんでした = did not change

Japanese often organizes sentences as topic + comment, and は is the particle that marks that topic.

This is a very common learner question.

In this sentence, は is used because the speaker is presenting his principles as the topic and then making a statement about them: they did not change.

If you used が instead, the nuance would shift. が tends to identify or highlight the subject more directly, often as new information or something being singled out.

Compare the feeling:

• 彼の主義は変わりませんでした。
  As for his principles, they did not change.
• 彼の主義が変わりませんでした。
  This is less natural in isolation, but could work in a context where you are specifically emphasizing that his principles were the thing that did not change.

So は is the more natural default here.

It comes from the verb 変わる, which means to change.

The dictionary form is:

• 変わる = to change

The sentence uses the polite negative past form:

• 変わりませんでした = did not change

So the breakdown is:

• 変わる → dictionary form
• 変わります → polite non-past
• 変わりません → polite negative non-past
• 変わりませんでした → polite negative past

This is why the sentence means did not change.

It is the polite negative past form of 変わる.

Step by step:

1. 変わる
   dictionary form

2. 変わります
   polite form

3. 変わりません
   polite negative

4. 変わりませんでした
   polite negative past

So the ending ませんでした means did not ... in polite speech.

This is a very common pattern:

• 行きませんでした = did not go
• 食べませんでした = did not eat
• 分かりませんでした = did not understand
• 変わりませんでした = did not change

変わる is an intransitive verb. That means something changes by itself, or at least the sentence describes the thing that undergoes change, not the thing doing the changing.

So:

• 主義が変わる / 主義は変わる = principles change

The related transitive verb is 変える, which means to change something:

• 彼は主義を変えた。 = He changed his principles.

But in your sentence:

• 彼の主義は変わりませんでした。 = His principles did not change.

So this is not were not changed. It is simply did not change.

This is a great thing to notice.

ました by itself is polite past:

• 変わりました = changed

But ませんでした is polite negative past:

• 変わりませんでした = did not change

So the sentence is specifically saying that his principles did not change.

A quick comparison:

• 変わりました = changed
• 変わりませんでした = did not change

It is polite, but not extremely formal.

The verb ending ました / ませんでした is the standard polite style, often used in:

• normal conversation with people you are not close to
• classroom Japanese
• speeches
• writing with a polite tone

A plain-form version would be:

• 彼の主義は変わらなかった。

That means the same thing, but sounds less polite and more casual or neutral.

Yes, you may hear 変わらなかったです, especially in modern speech. It is understandable and common in conversation.

However, from a textbook or standard grammar point of view:

• 変わりませんでした is the cleaner polite form
• 変わらなかったです is a less formal spoken-style polite form

So if you are learning standard polite Japanese, 変わりませんでした is the safer form to use.

Because 変わる is intransitive.

Intransitive verbs do not take a direct object marked by を in the normal way. The thing that changes is the subject/topic, not an object.

So:

• 主義は変わりませんでした。 = The principles did not change.

But with the transitive verb 変える, you would use を:

• 彼は主義を変えませんでした。 = He did not change his principles.

That is a different grammatical structure.

It is similar, but not exactly the same.

• 彼の主義は変わりませんでした。
  His principles did not change.
  This describes the principles themselves as remaining unchanged.

• 彼は主義を変えませんでした。
  He did not change his principles.
  This focuses more on his action or decision not to change them.

English often treats these as almost the same, but Japanese distinguishes them clearly through 変わる vs 変える.

No, they are not the same.

彼の主義は means:

• his principles are the topic

This is the natural structure for saying something about his principles.

彼は主義が... would mean something more like:

• as for him, his principles ...

That structure is possible in some contexts, but it is less straightforward here and can sound awkward without a specific reason.

So for this sentence, 彼の主義は変わりませんでした is the normal and natural choice.

Japanese nouns usually do not show singular vs plural the way English nouns do.

So 主義 can refer to:

• a principle
• principles
• an ideology
• a doctrine

English has to choose one, so translators often pick principles or ideology depending on context.

If the meaning shown to you was His principles did not change, that is a natural translation. But His ideology did not change could also be correct in a different context.

Yes, grammatically it is perfectly natural.

The main thing to remember is that in actual conversation, Japanese often omits information that is already clear. So if everyone already knows who he is, a native speaker might simply say:

• 主義は変わりませんでした。

But if the speaker wants to be clear, contrast him with someone else, or the sentence is part of written narration, 彼の主義は変わりませんでした is completely fine.

The spaces are almost certainly just for learning purposes.

Normal Japanese writing does not usually put spaces between words, so this would normally be written as:

彼の主義は変わりませんでした。

Textbooks and beginner materials sometimes add spaces to help learners see the parts more clearly:

• 彼
• の
• 主義
• は
• 変わりませんでした

But in real Japanese text, you should expect no spaces.

Yes. Depending on context, it could be translated as:

• His principles did not change.
• His beliefs did not change.
• His ideology did not change.
• He did not abandon his principles.
  This last one is a freer translation, not a literal one.

The most literal core meaning is simply that his 主義 remained unchanged. The best English wording depends on what 主義 means in the larger context.

The structure is:

• 彼の主義 = his principles
• は = topic marker
• 変わりませんでした = did not change

So the pattern is:

• [topic] は [statement]

More literally:

• As for his principles, they did not change.

This is a very common Japanese sentence pattern and a good one to get used to.