Abstract: A target protein for viral vector-based anticancer therapy, and a binding molecule or a fragment thereof which specifically binds thereto are disclosed. A conformational epitope of protein A56, and a binding molecule or a fragment thereof which specifically binds thereto are disclosed. The A56-binding molecule or a fragment thereof, which binds to a conformational epitope of A56 forms a specific structural bond with A56 and shows high affinity thereto. Administering a vaccinia virus-based oncolytic virus, A56 is expressed on the cancer cell surface in various carcinomas. The A56-binding molecule or a fragment thereof effectively targets A56 that is specifically expressed on the cancer cell surface, which enables targeted therapy for cancer cells that have survived even infection with an oncolytic virus, thereby providing effective anticancer therapy.