kono interia ga suki da.

この means this and must come directly before a noun.

So:

• この
  • インテリア
• not これインテリア

A helpful comparison:

• これ = this one
• この = this ... before a noun

So このインテリア means this interior / this decor / this interior design.

Not exactly.

In Japanese, インテリア often refers to things like:

• interior decor
• interior design
• furnishings
• the overall look/style of a room

So it usually does not just mean the inside of something in the broad English sense. It often has a design or decor nuance.

Depending on context, このインテリア might mean:

• this decor
• this interior design
• this room style
• these furnishings

This is one of the most common questions, because English learners expect like to work like a normal verb.

But in Japanese, 好き does not behave like an ordinary action verb such as 食べる or 見る. Instead, 好き is treated more like an adjective-like word meaning liked or pleasing.

Because of that, the thing that is liked is often marked with が.

So:

• このインテリアが好きだ

is the normal pattern.

A very literal way to think about it is something like:

• This interior is pleasing / liked

That is why が appears instead of を.

No. 好き is not a verb.

It is usually taught as a na-adjective (or an adjectival noun, depending on the grammar framework you use).

That is why it does not conjugate like a verb. For example:

• 好きだ
• 好きです
• 好きじゃない
• 好きだった

These are not verb forms of 好き itself. They are forms built with 好き plus the copula.

This is also why learners should avoid thinking of 好き as a direct equivalent of the English verb to like.

だ is the plain-form copula.

It gives the sentence a casual, plain ending.

So:

• このインテリアが好きだ = plain / casual
• このインテリアが好きです = polite

In everyday conversation, the だ is also often dropped:

• このインテリアが好き。

That sounds very natural in casual speech.

It is omitted.

Japanese often leaves out subjects when they are obvious from context. In a sentence like this, the speaker is usually understood to be the one expressing the preference.

So even though there is no visible 私は, the sentence can naturally mean that I like it.

This omission is extremely common in Japanese and is one of the first things English speakers have to get used to.

Yes, but the nuance changes.

Compare:

• このインテリアが好きだ
• このインテリアは好きだ

With が, the sentence simply identifies this interior as the thing that is liked.

With は, the sentence makes this interior the topic, often with a contrastive feeling, such as:

• As for this interior, I like it
• This interior, at least, I like

So は can sound like there is an implied comparison with other interiors.

For a basic neutral statement, が好き is the standard pattern.

The structure is:

• このインテリア = this interior / this decor
• が = marks what is liked
• 好き = liked / pleasing / favorite
• だ = plain copula

So the sentence follows the common pattern:

• X が 好きだ

This is a very important pattern in Japanese, and you can use it with many nouns:

• 音楽が好きだ
• 猫が好きだ
• 日本料理が好きだ

No. Normally, Japanese is written without spaces:

• このインテリアが好きだ。

Spaces are often added only in beginner materials to make the sentence easier to read.

So for normal writing, you should write it without spaces.

The polite version is:

• このインテリアが好きです。

That is the most direct polite equivalent.

You could also make the sentence a little softer or more conversational depending on context, but 好きです is the standard polite form learners should know first.

Yes, absolutely.

好き can be used for:

• people
• animals
• objects
• styles
• activities
• foods
• places

So using it with インテリア is completely normal.

Examples:

• この色が好きだ。
• このデザインが好きだ。
• この雰囲気が好きです。

All of these are natural ways to express preference in Japanese.