The present invention provides a method of screening substances having property of causing apoptosis, and relates to a method of screening substances having property of causing apoptosis characterized by using cells which are expressing IAP (Integrin Associated Protein), and the relates to above screening method, wherein the cells used are myeloid cells, and relates to pharmaceutical compositions containing as the active ingredient the substances obtained by the above method, and the present invention makes it possible to differentiate, identify and screen readily and highly efficiently the substances, such as antibodies and the like, that have property of causing apoptosis on myeloid cells by using cells which are expressing IAP while using specific binding reactions of the substances, and the above specific substances thus obtained can be used by virtue of their characteristics as the active ingredient of pharmaceutical compositions such as anticancer agents and medicines for myelocytic leukemia and the like.