Disclosed is an excellent peptide-producing protein. Also disclosed is a process for producing a peptide with high efficiency, or the like. The process comprises reacting an amine component with a carboxy component in the presence of at least one of the following proteins (I) and (II) to produce a peptide: (I) a mutant protein comprising an amino acid sequence having one or more of the mutations shown in mutation types 1 to 68, 239 to 290 and 324 to 377 in the amino acid sequence depicted in SEQ ID NO: 2; and (II) a mutant protein comprising an amino acid sequence having one or more of the mutations shown in mutation types L1 to L335 and M1 to M642 in the amino acid sequence depicted in SEQ ID NO: 208.