The problem addressed by the present invention is to provide a novel medicinal agent for the prevention and/or treatment of a viral infection. The present invention provides a medicinal agent for the prevention and/or treatment of a viral infection other than hepatitis C, and contains as the active ingredient the compound represented by general formula (I) or a salt thereof [In the formula, X represents a nitrogen atom or C-R4； R1, R2, R3, and R4 each independently represent a hydrogen atom, C1 - 6 alkyl group, C2 - 6 alkenyl group, C2 - 6 alkynyl group, C1 - 6 alkoxy group, halogen atom, nitro group, amino group, C1 - 3 mono- or di-alkyl amino group, C1 - 3 alkyl carbonylamino group optionally substituted by a phenyl group, benzoyl amino group, trifluoromethyl group, azido group, carboxyl group, C1 - 3 alkyl carbonyl group, C1 - 3 alkoxy carbonyl group, carbamoyl group, naphthyl group, optionally substituted heteroaryl group, styryl group, C1 - 3 alkyl thio group, C1 - 6 hydroxyalkyl group, or a group having the structure represented by general formula (1) in the description； R2 and R3, or R3 and R4 are optionally crosslinked； R5 represents an optionally substituted C1 - 5 straight chain alkylene group, with substituents on the alkylene group optionally bonded together to form a ring structure].
