Modified sarcosine oxidase, and gene and production method therefor

A modified sarcosine oxidase wherein said modified sarcosine oxidase is a protein comprising an amino acid sequence having 80% or more identity with the amino acid sequence of SEQ ID NO:

• 2, 3, or 4, wherein, with regard to said protein, the amino acid at the position corresponding to position 320 in SEQ ID NO:
• 1 is asparagine and the amino acid at the position corresponding to position 324 in SEQ ID NO:
• 1 is glycine, said protein having sarcosine oxidase activity with reduced reactivity to L-proline compared to that of a protein having a sequence identical to SEQ ID NO:
• 1.