A tumor antigen gene is identified by screening a cDNA library derived from a gastric cancer cell line that can induce gastric cancer antigen specific cytotoxic T cell (CTL) by means of hybridization and PCR utilizing an amino acid sequence of peptide fragment of a known gastric cancer antigen protein, introducing a selected cDNA clone into a cell of gastric cancer cell line that cannot induce gastric cancer antigen specific CTL so that the clone should be expressed in the cell, and selecting a transgenic cell that has acquired the ability to induce CTL. According to the present invention, there are provided a protein capable of inducing immune response against human gastric cancer, DNA encoding the protein, as well as vaccine for treatment and prevention of human gastric cancer, and agent for treatment and prevention of human gastric cancer.