<;P>;PROBLEM TO BE SOLVED: To find a peptide useful as an agent for treating and/or preventing cancer, and to provide the use of the peptide as an immunity-inducing agent. <;P>;SOLUTION: A cDNA encoding a protein binding to an antibody specifically existing in a serum originated from a cancer-carrying living body is obtained by SEREX method using a cDNA library originated from canine testis and using the serum of a cancer-carrying dog, and a polypeptide having a specific amino acid sequence is produced on the basis of the cDNA. The polypeptide can induce immunity to living bodies, and can regress the tumor of a cancer-carrying living body. <;P>;COPYRIGHT: (C)2009,JPO&INPIT