A modified creatinine amidohydrolase having creatinine amidohydrolase activity wherein: the amino acid at position 175 in the amino acid sequence shown in SEQ ID NO: 1 of the Sequence Listing, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with an amino acid selected from the group consisting of threonine, glutamine, asparagine, isoleucine, serine, and leucine; the amino acid at position 175 in the amino acid sequence shown in SEQ ID NO: 2 of the Sequence Listing, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with an amino acid selected from the group consisting of glutamine, lysine, serine, histidine, leucine, cysteine, glutamic acid, phenylalanine, and tryptophan; the amino acid at position 175 in the amino acid sequence shown in SEQ ID NO: 3 of the Sequence Listing, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with an amino acid selected from the group consisting of methionine, glutamine, lysine, serine, threonine, arginine, and histidine; an amino acid at position 124 in the amino acid sequence shown in SEQ ID NO: 2, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with tryptophan; an amino acid at position 78 in the amino acid sequence shown in SEQ ID NO: 2, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with threonine or arginine; an amino acid at position 122 in the amino acid sequence shown in SEQ ID NO: 2, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with serine; or an amino acid at position 43 in an amino acid sequence shown in at least one of SEQ ID NOS: 1, 2, and 7 to 10, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with aspartic acid or glutamic acid. the amino acid at position 175 in the amino acid sequence shown in SEQ ID NO: 1 of the Sequence Listing, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with an amino acid selected from the group consisting of threonine, glutamine, asparagine, isoleucine, serine, and leucine; the amino acid at position 175 in the amino acid sequence shown in SEQ ID NO: 2 of the Sequence Listing, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with an amino acid selected from the group consisting of glutamine, lysine, serine, histidine, leucine, cysteine, glutamic acid, phenylalanine, and tryptophan; the amino acid at position 175 in the amino acid sequence shown in SEQ ID NO: 3 of the Sequence Listing, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with an amino acid selected from the group consisting of methionine, glutamine, lysine, serine, threonine, arginine, and histidine; an amino acid at position 124 in the amino acid sequence shown in SEQ ID NO: 2, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with tryptophan; an amino acid at position 78 in the amino acid sequence shown in SEQ ID NO: 2, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with threonine or arginine; an amino acid at position 122 in the amino acid sequence shown in SEQ ID NO: 2, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with serine; or an amino acid at position 43 in an amino acid sequence shown in at least one of SEQ ID NOS: 1, 2, and 7 to 10, or at a position equivalent thereto in an amino acid sequence of creatinine amidohydrolase derived from organisms other than Pseudomonas putida (PS-7), is substituted with aspartic acid or glutamic acid.