Disclosed is an antibody against a secreted form of GPC3 capableof detecting a secreted form of glypican 3 (GPC3) in a testsample. It is possible to determine whether a subject suffersfrom cancer, in particular hepatoma. Also disclosed is anantibody against GPC as well as a cell disrupting agent andan anti-cancer agent comprising the same, which can disruptcells, in particular cancer cells.