[Problem] To provide a novel anticancer drug which is useful for treating prostatic cancer associated with an androgen receptor mutation.[Solution] As the results of intensive studies on mutated androgen-associated diseases for which the conventional anti-androgen drugs are inefficacious, the present inventors found that a compound, said compound being the active ingredient of a medicinal composition according to the present invention, exhibits an effect of inhibiting the transcriptional activation in a human mutated androgen receptor (AR) and has an excellent antitumor effect on a mouse carrying human prostatic cancer cells, thereby completing the present invention. The compound that is the active ingredient of the medicinal composition according to the present invention is useful for treating diseases such as prostatic cancer in which a series of androgen receptors participate.
