THE PRESENT INVENTION PROVIDES A POLYPEPTIDE HAVING A WIDE SUBSTRATE SPECIFICITY AND HAVING A ω3 FATTY ACID DESATURATION ACTIVITY, WHICH MAKES EFFICIENTLY UNSATURATED BOND AT ω3 POSITION, AND A POLYNUCLEOTIDE CODING FOR THE SAME. BY EXPRESSING THE POLYPEPTIDE IN THE ORGANISM, MASS PRODUCTION OF N-3 SERIES PUFAS IS ENABLED. SPECIFICALLY, THE POLYPEPTIDE HAVING A ω3 FATTY ACID DESATURATION ACTIVITY AND CONSISTING OF THE AMINO ACID SEQUENCE REPRESENTED BY SEQ ID NO: 1, A POLYNUCLEOTIDE CODING FOR A POLYPEPTIDE HAVING A ω3 FATTY ACID DESATURATION ACTIVITY THAT CONSISTS OF THE BASE SEQUENCE REPRESENTED BY SEQ ID NO: 2 OR SEQ ID NO: 3, AND THE LIKE IS USEFUL FOR PRODUCTION OF N-3 SERIES FATTY ACIDS.
