It is an object of the present invention to provide utilization of a UCA1 gene that is a host regulatory factor that enhances replication and/or propagation of a vaccinia virus, in order to effectively carry out cancer virotherapy using the vaccinia virus. The present invention relates to: a method for predicting and evaluating the cancer therapeutic effects of a vaccinia virus, which comprises measuring the expression of a UCA1 gene in the cancer cells of a cancer patient, and then predicting that a vaccinia virus exhibits cancer therapeutic effects on the patient, when the UCA1 gene has been expressed therein; and a vaccinia virus into which a UCA1 gene has been expressibly introduced.