An object of the present invention is to provide a recombinant LPA phosphatase capable of specifically hydrolyzing LPA, which is useful for elucidation of the metabolism pathway of LPA, and also for diagnosis and treatment of various diseases with which LPA is associated; a method capable of simply and inexpensively determining LPA associated with various diseases; and a kit for determination suitable for the method. The present invention has succeeded in purifying the LPA phosphatase using bovine brain as raw material, and further in cloning human LPA phosphatase gene. The present invention is accomplished by a DNA encoding a peptide comprising the amino acid sequence of SEQ ID NO:1; a DNA comprising the nucleotide sequence of SEQ ID NO:2; a protein encoded by the DNA; an expression vector carrying the DNA; a transformant harboring the expression vector; a method for producing a recombinant lysophosphatidic acid phosphatase by the transformant; a method for determination of LPA by the protein; a determination reagent for LPA by the protein; a kit for diagnosis, comprising the reagent for determination, and the like.