Provided is a pharmaceutical which exhibits sufficient anticancer effects by using an antibody which binds to a mutant CALR protein and another anticancer agent in combination. Provided is a pharmaceutical for preventing and/or treating a cancer, comprising (A) an antibody which specifically binds to a mutant calreticulin protein or a functional fragment thereof and (B) at least one drug selected from the group consisting of an alkylating agent, a platinum preparation, an antimetabolite, a ribonucleotide reductase inhibitor, a nucleotide analog, a topoisomerase inhibitor, a microtubule polymerization inhibitor, an antitumor antibiotic, an interferon, a cytokine preparation, a molecular targeting drug, a nucleic acid synthesis inhibitor, a JAK inhibitor, and a cancer immunotherapeutic agent in combination.