The present invention relates to an antibody that binds to GARP and is useful as a therapeutic agent against tumors, and a method for treating a tumor using the antibody. The present invention addresses the problem of providing an antibody which can be used as a medicine that inhibits the function of Treg in a tumor and thus exhibits a therapeutic effect, and a method for treating a tumor using the antibody. An anti-GARP antibody that binds to GARP and exhibits a Treg-function inhibiting activity and an ADCC activity is obtained. Moreover, a medicinal composition for treating tumors, said composition containing the antibody, is obtained.
