In order to identify a novel gene responsible for parthenocarpy and to provide use of the gene, the parthenocarpy regulatory gene of the present invention includes a polynucleotide (1) that encodes an amino acid sequence represented by SEQ ID NO: 1, (2) that encodes an amino acid sequence (i) having a sequence identity of 75% or higher relative to the amino acid sequence represented by SEQ ID NO: 1, (3) that encodes an amino acid sequence in which 1 to 98 amino acids are substituted, etc. in the amino acid sequence represented by SEQ ID NO: 1, or (4) that is hybridized with a polynucleotide, which has a sequence complementary to the polynucleotide for encoding the amino acid sequence represented by SEQ ID NO: 1 under a stringent condition.