The present invention provides a bispecific antibody comprising IL-12 or a variant thereof and an antigen binding site that specifically binds to CD20. The bispecific antibody exhibits an anticancer effect by IL-12. In particular, when the anti-CD20 antibody is implemented in one antibody, IL-12 is specifically localized to a tumor site by targeting CD20, which is specifically expressed in a tumor at a high level, thereby efficiently treating cancer. Therefore, the bispecific antibody can be utilized as a pharmaceutical composition for anticancer treatment, and thus has a high potential for industrial application.