PROBLEM TO BE SOLVED: To provide a novel compound having P2X7 receptor inhibitory action, and a pharmaceutical composition having P2X7 receptor inhibitory action.SOLUTION: Six-membered heterocyclic derivatives and a pharmaceutical composition containing them are illustrated below.SELECTED DRAWING: None【課題】P2X7受容体阻害作用を有する新規化合物およびP2X7受容体阻害作用を有する医薬組成物の提供。【解決手段】下記に例示される6員複素環誘導体及びそれらを含有する医薬組成物。【選択図】なし