To obtain the subject new gene, having a specific amino acid sequence and capable of coding a cytochrome P450cc23 which is an enzyme capable of hydroxylating the 23-position of a vitamin D3 derivative and mass-producing the enzyme useful for the production, etc., of an active type vitamin D3.

This cytochrome P450cc23 gene is a new DNA, having an amino acid sequence represented by the formula and capable of coding a polypeptide comprising the cytochrome P450cc23 which is an enzyme capable of hydroxylating the 23-position of a vitamin D3 derivative. The new DNA is further capable of industrially producing 23,25-dihydroxyvitamin D3 from 25-hydroxyvitamin D3 or 23, 24,25-trihydroxyvitamin D3 from 24,25-dihydroxyvitamin D3 and is useful for mass-producing an active type vitamin D3. The DNA is obtained by extracting an mRNA from the kidney of a guinea pig according to a conventional method, preparing a cDNA library by using the extracted mRNA and then screening the prepared cDNA library with a probe comprising a part of a DNA capable of coding the cytochrome P450cc23.