A process for producing a dipeptide, which comprises: allowing an enzyme source and one or more kinds of amino acids to be present in an aqueous medium, said enzyme source being a culture of (a) a microorganism; or (b) a treated matter of the culture of (a); allowing the dipeptide to form and accumulate in the aqueous medium; and recovering the dipeptide from the medium, wherein said microorganism is a microorganism in which the activities of one or more kinds of peptidases and one or more kinds of proteins having peptide-transporting activity (hereinafter referred to also as peptide-transporting proteins) are reduced or lost as compared to the parent strain, said parent strain belonging to the genus Escherichia, Bacillus, Corynebacterium or Saccharomyces, and wherein said microorganism has the ability to produce a dipeptide, wherein said ability to produce a dipeptide is the ability to produce a protein according to any of to below: a protein having the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68; a protein consisting of an amino acid sequence wherein one or more amino acid residues are deleted, substituted or added in the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68 and having the activity to synthesize a dipeptide; a protein consisting of an amino acid sequence which has 65% or more homology to the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68 and having the activity to synthesize a dipeptide; and a protein having an amino acid sequence which has 80% or more homology to the amino acid sequence shown in SEQ ID NO: 33 and having the activity to synthesize a dipeptide, and wherein the treated matter of the culture is concentrated culture, dried culture, cells obtained by centrifuging the culture, or a product obtained by subjecting the cells to drying, freeze-drying or immobilization. allowing an enzyme source and one or more kinds of amino acids to be present in an aqueous medium, said enzyme source being a culture of (a) a microorganism; or (b) a treated matter of the culture of (a); (a) a microorganism; or (b) a treated matter of the culture of (a); allowing the dipeptide to form and accumulate in the aqueous medium; and recovering the dipeptide from the medium, wherein said microorganism is a microorganism in which the activities of one or more kinds of peptidases and one or more kinds of proteins having peptide-transporting activity (hereinafter referred to also as peptide-transporting proteins) are reduced or lost as compared to the parent strain, said parent strain belonging to the genus Escherichia, Bacillus, Corynebacterium or Saccharomyces, and wherein said microorganism has the ability to produce a dipeptide, wherein said ability to produce a dipeptide is the ability to produce a protein according to any of to below: a protein having the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68; a protein consisting of an amino acid sequence wherein one or more amino acid residues are deleted, substituted or added in the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68 and having the activity to synthesize a dipeptide; a protein consisting of an amino acid sequence which has 65% or more homology to the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68 and having the activity to synthesize a dipeptide; and a protein having an amino acid sequence which has 80% or more homology to the amino acid sequence shown in SEQ ID NO: 33 and having the activity to synthesize a dipeptide, a protein having the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68; a protein consisting of an amino acid sequence wherein one or more amino acid residues are deleted, substituted or added in the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68 and having the activity to synthesize a dipeptide; a protein consisting of an amino acid sequence which has 65% or more homology to the amino acid sequence shown in any of SEQ ID NOs: 19 to 25 and 68 and having the activity to synthesize a dipeptide; and a protein having an amino acid sequence which has 80% or more homology to the amino acid sequence shown in SEQ ID NO: 33 and having the activity to synthesize a dipeptide, and wherein the treated matter of the culture is concentrated culture, dried culture, cells obtained by centrifuging the culture, or a product obtained by subjecting the cells to drying, freeze-drying or immobilization.