Provided is a novel medicament capable of reducing the side effects of metformin or a pharmaceutically acceptable salt thereof and useful as an anti-malignant tumor agent, in which metformin or a pharmaceutically acceptable salt thereof and dihydroquercetin or a pharmaceutically acceptable salt thereof are combined.本發明提供一種新穎藥物，其能夠減少二甲二胍(metformin)或其醫藥上可接受之鹽的副作用，並可作為抗惡性腫瘤劑，其中係將二甲二胍或其醫藥上可接受之鹽與二氫槲皮素(dihydroquercetin)或其醫藥上可接受之鹽組合。
