The present invention relates to tumor antigen proteins or genes derived from polo-like kinase 1. As a result of the formation of a complex by binding polo-like kinase 1-derived proteins or variants having characteristics functionally identical to the proteins with MHC class I antigens or II antigens, the complex can be recognized by cytotoxic T lymphocytes. Therefore, the polo-like kinase 1-derived proteins or variants are identified as a tumor antigen which can be generally used in tumor immunotherapy.
