The present invention is intended to provide a novel anticancer agent which is effective to a cancer. After administering an agent prepared using burdock fruit extract to a pancreas cancer patient so that a dose of arctigenin was 100 mg or more per day, the tumor reducing effect was observed, and, in addition, lowering of tumor markers was confirmed. The present invention provides an anticancer agent containing arctigenin, wherein a dose of the arctigenin is 100 mg or more per day. In addition, the present invention provides the anticancer agent containing arctigenin and arctiin at a weight ratio of arctigenin/arctiin=0.7 to 1.3.