Disclosed is a novel phosphatidate phosphatase gene. Specifically disclosed are: a nucleotide sequence represented by SEQ ID NO: 1 or SEQ ID NO: 7 SEQ ID NO: 4 or SEQ ID NO: 9 or SEQ ID NO: 5 or SEQ ID NO: 10 and an amino acid sequence represented by SEQ ID NO: 2 or SEQ ID NO: 6.