The present invention relates to a pharmaceutical composition for preventing or treating cancer, comprising an anticancer virus and hydroxyurea as effective components. The pharmaceutical composition for preventing or treating cancer comprising an anticancer virus and hydroxyurea as effective components according to the present invention exhibits superior tumor suppression effect as compared to a conventional case where only an anticancer virus is administered； and can kill even the cancer cells that are resistant to anticancer viruses. Accordingly, the pharmaceutical composition for preventing or treating cancer of the present invention may be beneficially used in treating cancer.
