The purpose of the present invention is to discover a target molecule expressed cancer-specifically, to provide an anticancer agent with which it is possible to treat cancer by acting specifically on this target molecule, and to provide a method for testing for cancer, the method including a step for measuring a target molecule in a sample. The present invention provides an anticancer agent that includes, as an active ingredient, an anti-transmembrane-protein-180 (TMEM-180) antibody or an antigen-binding fragment thereof. The present invention also provides a cancer testing method that includes a step for measuring the TMEM-180 level in a sample collected from a subject.
