PROBLEM TO BE SOLVED: To provide a new xanthine oxidase inhibitor and a hyperuricemia-therapeutic agent.SOLUTION: There are provided a xanthine oxidase inhibitor and a hyperuricemia-therapeutic agent, comprising a condensed pyrimidine derivative of the general formula or a salt thereof as an active ingredient. (Wherein, Rrepresents phenyl which may be substituted with F; Rrepresents cyano or nitro; Rrepresents hydroxyl; X represents O; and Y represents S).【課題】新規なキサンチンオキシダーゼ阻害剤及び高尿酸血症治療剤の提供。【解決手段】一般式(式中、R1~3、X、Yは特定の基。の縮合ピリミジン誘導体又はその塩を有効成分として含有するキサンチンオキシダーゼ阻害剤、及び高尿酸血症治療剤。【選択図】なし