It is found that a nucleoside derivative represented by the following general formula (1) has an anti-viral activity and is less toxic to host cells.[in the formula, Rrepresents a hydrogen or halogen atom, Rrepresents a hydrogen or halogen atom, Rrepresents a cyano group, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, a halogen atom, or an azido group, Rrepresents an amino group, a hydrogen atom, a halogen atom, or a hydroxy group, Rrepresents a nitrogen atom or a methine group, Rrepresents a hydrogen atom or a hydroxy group, and Rrepresents a hydrogen atom or a hydroxy group.]
