Provided is a novel compound which is capable of inhibiting the formation of an infectious prion protein via binding to a normal prion protein. Specifically provided is a compound represented by formula (1). In formula (1), X represents a carbon atom or a nitrogen atom； R1 and R2 may be either the same or different and represent a hydrogen atom, an oxygen atom, a halogen atom, a hydroxy group, a mercapto group, a cyano group, a carboxy group, a carbamoyl group, an alkoxycarbonyl group, an acyloxy group, an acyl group, an optionally substituted hydrocarbon group, an optionally substituted heterocyclic group, an optionally substituted amino group, etc.； and R3 to R6 may be either the same or different and represent a hydrogen atom, a halogen atom, an optionally substituted hydrocarbon group, an optionally substituted heterocyclic group, etc., provided that at least one of R1 and R2 represents a group other than hydrogen atom.
