hoshousho ni seizoubangou ga kaite arimasu.

The serial number is written on the warranty card.

Breakdown of hoshousho ni seizoubangou ga kaite arimasu.

• が: subject particle
• 書かく: to write
• に: location particle
• 〜て ある: resultant state (intentionally)

Questions & Answers about hoshousho ni seizoubangou ga kaite arimasu.

Why is に used after 保証書?

Here, に marks the place where something is located or where a result exists.

So 保証書に製造番号が書いてあります means the serial number exists in a written form on the warranty card.

In this kind of sentence, に often translates as on, in, or at, depending on the natural English wording.

Pattern:

• A に B が書いてある = B is written on/in A

Why is 製造番号 marked with が instead of を?

Because this sentence is describing a state, not the action of writing.

Compare these:

• 製造番号を書く
  = write the serial number
  Here, 製造番号 is the direct object, so it takes を.

• 製造番号が書いてある
  = the serial number is written
  Here, the serial number is the thing in the resulting state, so it takes が.

This is very common with the 〜てある pattern: the thing affected by the action shows up as the subject with が.

What does 書いてあります mean grammatically?

書いてあります is 書く in the 〜てある pattern.

Structure:

• 書く → 書いて
• 書いてある = to be in the state of having been written

This pattern means:

• someone intentionally did the action
• the result still remains

So 書いてあります does not focus on the person writing. It focuses on the fact that the writing is there now.