PROBLEM TO BE SOLVED: To provide compounds as γ-Secretase inhibitors which prevent the generation of the active domain of Notch molecules, useful for neurodegenerative disease such as Alzheimer's disease and cancer, and pharmaceutical compositions comprising the compounds.SOLUTION: This invention provides a coumarin-based compound represented by the formula, and a pharmaceutical composition comprising the compound. [Xs independently represent O, NH or S; Rs independently represent halogen, C-Calkoxy, cyano, amino, hydroxy or C-Calkyl; Ris C-Calkylen or C-Calkenylene; and t is an integer of 2-5].【課題】アルツハイマー病等の神経変性疾患及び癌に対して有用な、ノッチ分子の活性ドメインの生成を防止するγ-セレクターゼ阻害剤である化合物、及び該化合物を含有する医薬組成物の提供。【解決手段】下式が代表例のクマリン系化合物、及び該化合物を含有する医薬組成物。[Xは各々独立にO、NH又はS;R1は各々独立にハロゲン、C1~C8アルコキシ、シアノ、アミノ、ヒドロキシ又はC2~C8アルキル;R2はC1~C8アルキレン又はC2~C8アルケニレン;tは2~5の整数]【選択図】なし