The present invention addresses the problem of discovering and providing an effective cancer therapy by means of a drug. Provided is a drug for cancer therapy characterized by administering a combination between: a compound represented by a general formula (I) (wherein, all symbols are as described in the description), a salt thereof, a solvate thereof, an N-oxide thereof, or an Ax1 inhibitor as a prodrug of those; and an immune checkpoint inhibitor (e.g., anti-PD-1 antibody, etc.). The combination according to the present invention exerts a strong anti-tumor effect, and thereby is useful in cancer therapy.