PROBLEM TO BE SOLVED: To provide a novel endometriosis preventive and/or therapeutic agent.SOLUTION: An endometriosis preventive and/or therapeutic agent comprises 3-bis-(4-methoxyphenyl)methylene-2-indolinone represented by the formula (1) or its pharmacologically acceptable salt as an active ingredient.COPYRIGHT: (C)2015,JPO&INPIT【課題】新規な子宮内膜症の予防剤及び/又は治療剤の提供。【解決手段】下記式(1)で表される3-ビス-(4-メトキシフェニル)メチレン-2-インドリノン又はその薬学的に許容される塩を有効成分とする、子宮内膜症の予防剤及び/又は治療剤。【化1】【選択図】図1