An HCV/GBV-B chimeric virus which maintains the replication function of HCV and is capable of infecting tamarin is disclosed in order to construct an HCV animal model which can be used as a development or evaluation system for therapeutic agents for HCV. The HCV/GBV-B chimeric RNA comprises an RNA of hepatitis C virus and an RNA of GB virus-B, wherein the RNA of hepatitis C virus comprises an RNA encoding leucine at the 1804th position and lysine at the 1966th position in the amino acid sequence of the polyprotein of hepatitis C virus.