Disclosed are novel anti platelet agents and novel compounds which can be active ingredients of the novel anti platelet agents. Specifically disclosed is an anti platelet agent which contains a compound represented by formula I or a pharmacologically acceptable salt thereof as an active ingredient. (In the formula X represents N or CR X X may be the same or different and each represents a nitrogen atom or a carbon atom R R may be the same or different and each represents a hydrogen atom an optionally substituted alkyl group an optionally substituted alkoxy group an optionally substituted alkylthio group an alkenyl group a cycloalkyl group a halogen group a cyano group a hydroxyl group or an amino group which may be substituted by one or two alkyl groups R represents an optionally substituted aryl group or an optionally substituted heteroaryl group and R represents an optionally substituted aryl group or an optionally substituted heteroaryl group.)
