The present invention develops a novel technology that is able to easily perform antigen-specific CTL induction for any given antigen. The present invention provides a cytotoxic T cell inducing composition containing: an anti-CD28 antibody； a solid support body at which the anti-CD28 antibody has been solid-phased； and a soluble peptide that can bond to an MHC class I molecule. In the cytotoxic T cell inducing composition, there are cases of the soluble peptide that can bond to an MHC class I molecule being presented as an antigen by means of an HLA compliant HLA complex of the patient and being recognized by the cytotoxic T cells. The present invention provides a tumor treatment drug composition. The tumor treatment drug composition contains the cytotoxic T cell inducing composition, the soluble peptide that can bond to an MHC class I molecule contains a portion of the amino acid sequence of a specific antigen protein of tumor cells, and the cytotoxic T cells recognize the tumor cells. The specific antigen protein of the tumor cells can be WT-1.
