The present invention relates to an antibody that binds to GARP and is useful as a therapeutic agent for a tumor, and a method for treating a tumor using the aforementioned antibody. It is an object of the present invention to provide an antibody, which inhibits the function of Treg in a tumor and is thereby used as a pharmaceutical product having therapeutic effects, a method for treating a tumor using the aforementioned antibody, and the like. An anti-GARP antibody that binds to GARP and exhibits inhibitory activity to Treg function and exhibits ADCC activity is obtained, and moreover a pharmaceutical composition for use in tumor therapy, comprising the aforementioned antibody, etc. is obtained.