An object of the present invention is to provide novel pharmaceutical compositions using anti-GRP78 antibodies. More particularly, the present invention provides a novel method of cancer treatment using anti-GRP78 antibodies, novel cell growth inhibitors and anticancer agents that contain anti-GRP78 antibodies, as well as novel anti-GRP78 antibodies. The present inventor prepared antitumor antibodies to target GRP78, the localization of which in cancer cells changed to the cell membrane. The inventor successfully obtained an anti-GRP78 antibody that would bind specifically to the cell surface of cancer cells, leading to the accomplishment of the above-mentioned objects.