PROBLEM TO BE SOLVED : To provide a novel pharmaceutical capable of reducing the side effects of metformin or a pharmaceutically acceptable salt thereof and useful as an anti-malignant tumor agent, particularly an agent for preventing or treating pancreas cancer. SOLUTION : A pharmaceutical is characterized by containing metformin or a pharmaceutically acceptable salt thereof, and dihydroquercetin or a pharmaceutically acceptable salt thereof in one formulation, or characterized by using a pharmaceutical composition containing metformin or a pharmaceutically acceptable salt thereof, and a pharmaceutical composition containing dihydroquercetin or a pharmaceutically acceptable salt thereof, which are separately formulated and combined with each other. SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT