The purpose of the present invention is to provide an anticancer agent which includes as an active ingredient a compound having excellent tumor cell selectivity and novel anticancer effects. The purpose of the present invention is particularly to provide an anticancer agent that is effective against leukemia and is highly safe. By the present invention, a pharmaceutical composition is provided which includes hydroxyalkylated cyclodextrin as an active ingredient having anticancer activity. The present invention particularly provides an anticancer agent for leukemia which includes hydroxypropyl-&bgr;-cyclodextrin as an active ingredient having anticancer activity.