The present invention provides a protein having dipeptide-synthesizing activity, a DNA encoding the protein, a recombinant DNA containing the DNA, a transformant obtained via transformation with the recombinant DNA, a process for producing a protein having dipeptide-synthesizing activity using the transformant, a process for producing a dipeptide using a protein having dipeptide-synthesizing activity, and a process for producing a dipeptide using a culture or the like of a transformant or a microorganism that produces a protein having dipeptide-synthesizing activity as an enzyme source.