The present invention relates to: a method for activating a helper T cell which comprises a step wherein a helper T cell is activated by adding a WT1 peptide to an antigen presenting cell and the like. The WT1 peptide is capable of binding to one MHC class II molecule which is HLA DRB1*0101 molecule HLA DRB1*0401 molecule HLA DRB1*0403 molecule HLA DRB1*0406 molecule HLA DRB1*0803 molecule HLA DRB1*0901 molecule HLA DRB1*1101 molecule HLA DRB3*0202 molecule HLA DRB4*0101 molecule HLA DPB1*0201 molecule or HLA DPB1*0301 molecule.