A polypeptide possessing a sphingolipid ceramide deacylase activity; a nucleic acid encoding the polypeptide; a recombinant DNA comprising the nucleic acid; a carrier for introducing into a cell, carrying the nucleic acid or the recombinant DNA; a transformant harboring the nucleic acid or the recombinant DNA; an oligonucleotide probe or primer for the nucleic acid; a method for detecting the nucleic acid using the probe or the primer and a kit usable therefor; an antibody or a fragment thereof against the polypeptide; and a method for detecting the polypeptide using the antibody or a fragment thereof and a kit usable therefor. According to the present invention, there can be applied to engineering of sphingolipids, and to treatments for diseases such as diseases of nervous system (for instance, neurodegenerative diseases and the like), leukemia and wounds.