Disclosed is an antibody which can bind to GPR49 protein and which has a cell proliferation-inhibitingactivity against a cell capable of producing GPR49 protein. The cell proliferation-inhibitingactivity may be a cytotoxic activity such as an antibody-dependent cytotoxicityor a complement-dependent cytotoxicity. Also disclosed are: a pharmaceuticalcomposition； a cell proliferation inhibitor； and an anti-cancer agent, eachof which comprises the antibody as an active ingredient. The cancer may be gastriccancer, colorectal cancer, hepatocellular cancer, lung cancer, prostate cancer,ovarian cancer, Ewing sarcoma, or glioma. Further disclosed are: a method forthe diagnosis of cancer by detecting GPR49 protein or the expression of a geneencoding GPR49 protein； and a diagnosis agent and a kit for use in the method.
