The invention relates to an anti-cancer agent containing α-chain protein (α-fragment) of HGF (hepatocyte growth factor) as an active ingredient. The active ingredient of α-fragment has a specific suppressing effect on invasion and metastasis of cancer cells such as gallbladder cancer, lung cancer and other, which are highly metastatic and result in a high mortality. Therefore, the agent of the invention is used in treatment and prevention of cancer as an anti-cancer agent, and is extremely useful clinically.