PROBLEM TO BE SOLVED: To provide an inhibitor of an estrogen receptor useful for treating cancer. 6- (2,4-dichlorophenyl) -5- [4-[(3S) -1- (3-fluoropropyl) pyrrolidine-3-yl] oxyphenyl] -8,9-dihydro-7H- A pharmaceutical composition containing benzo [7] annulene-2-carboxylic acid. [Selection diagram] None【課題】癌の処置に有用なエストロゲン受容体の阻害剤の提供。【解決手段】6-(2,4-ジクロロフェニル)-5-[4-[(3S)-1-(3-フルオロプロピル)ピロリジン-3-イル]オキシフェニル]-8,9-ジヒドロ-7H-ベンゾ[7]アヌレン-2-カルボン酸を含有する医薬組成物。【選択図】なし