A novel process for preparing tumor-specific T cells is disclosed. According to the invention, antitumor-active, tumor-specific T cells are prepared by transducing a TCR gene from a tumor-specific CTL into antitumor-active T cells that have been nonspecifically activated, thus enabling tumor-specific cellular immunotherapy to be carried out from even small amounts of blood. MHC class I-restricted, tumor-specific Th cells are obtained by the method, allowing for the production of cells that react with tumor cells expressing an MHC class I molecule and show a helper activity and an antitumor activity.