A neutral/alkaline ceramidase derived from a mammal; an antibody specifically binding thereto; a probe and primer which are capable of specifically hybridizing thereto; a method for producing the ceramidase by a genetic engineering means; a method for detecting the ceramidase or the gene; and a method of controlling an amount of a ceramide in a cell and/or in a tissue. The present invention is useful as a reagent for lipid engineering for analyzing a structure, functions, and the like of a ceramide, and in its applications to diseases associated with the ceramide metabolism.