The present invention relates to a method for activating helper T cells, which includes the step of activating helper T cells by adding a WT1 peptide to antigen presenting cells, wherein the WT1 peptide has the ability to bind to any MHC class II molecule of an HLA-DRB1* 0101 molecule, an HLA-DRB1* 0401 molecule, an HLA-DRB1* 0403 molecule, an HLA-DRB1* 0406 molecule, an HLA-DRB1* 0803 molecule, an HLA-DRB1* 0901 molecule, an HLA-DRB1* 1101 molecule, an HLA-DRB3* 0202 molecule, an HLA-DRB4* 0101 molecule, an HLA-DPB1* 0201 molecule or an HLA-DPB1* 0301 molecule, and the like.