The invention provides a method for treating a cancer with a human FOLR1-targeting drug by increasing an expression of folate receptor ± (hereinafter abbreviated to FOLR1) by using an antagonist for folic acid metabolism, a medicament for a cancer containing a human FOLR1-targeting drug for increasing an expression of FOLR1 by using an antagonist for folic acid metabolism and a method for enhancing a therapeutic effect of a human FOLR1-targeting drug by increasing an expression of FOLR1 in a cancer cell by using an antagonist for folic acid metabolism. For example, the invention provides a more effective therapeutic method using an antagonist for folic acid metabolism with a human FOLR1-targeting drug, for cancer patients in which an expression level of FOLR1 is low and in which an anti-tumor activity of the human FOLR1-targeting drug is not exhibited sufficiently or for cancer patients in which a treatment of a cancer expressing FOLR1 is to be further enhanced.
