To obtain a proline dipeptidase gene having the ability to hydrolyze a dipeptide having a structure of an aminoacyl-hydroxyproline and capable of mass-producing the proline dipeptidase by providing a specific base sequence.

This proline dipeptidase gene has a base sequence represented by the formula. A PstI-Xhol fragment of about 3 kb is cited as an example of a DNA fragment containing the proline dipeptidase gene and a recombinant pAPLD is cited as an example of a recombinant plasmid DNA containing the DNA fragment. A microorganism Escherichia coli DH1 holding the recombinant plasmid pAPLD is deposited as FERM P-16753.