How to calculate the total amount by month

Column C contains the cumulative sumif and row functions of column B.

=ARRAYFORMULA(if(B2:B="", "", sumif(row(B2:B), "<="&row(B2:B), B2:B)))

Currently, even if the date in column A is March, the total amount is calculated regardless of April.

I would like to start this again from ￥0 when the month changes.

I have little knowledge of functions, but I put month(B2:B) in the sumif condition, but it didn't work out so I asked you a question.
I would appreciate it if you could give me some advice.