The object aims to construct an HCV animal model which can be used for the development of an HCV therapeutic agent or in an evaluation system for an HCV therapeutic agent. Thus, disclosed is an HCV/GBV-B chimeric virus which maintains the replication function of an HCV and can infect tamarins. Also disclosed is HCV/GBV-B chimeric RNA which comprises RNA of a hepatitis C virus and RNA of a GB virus-B, wherein the RNA of the hepatitis C virus comprises RNA which encodes an NA4B protein containing a leucine residue at position-1804 and a lysine residue at position-1966 in the amino acid sequence for a polyprotein of the hepatitis C virus.
