Provided are a protein comprising the amino acid sequence as shown in SEQ ID NO: 2 and having prolidase activities, a prolidase gene coding for the protein, a prolidase gene comprising the nucleotide sequence as shown in SEQ ID NO: 1, recombinant DNA having the gene inserted into vector DNA, and a transformant or transductant comprising the recombinant DNA, and a method for producing prolidase using the transformant or transductant. The present invention can improve the prolidase through protein engineering. The present invention can be also used for improving microorganisms used in the production of enzymes for food processing and fermented foods.