Disclosed are an HCV gene having higher replication efficiency and higher reinfection efficiency than the known HCV gene of genotype 1b, an RNA replicon having this gene, a cell infected with this RNA replicon, which cell allows replication of HCV, and an HCV particle. The hepatitis C virus gene encodes an amino acid sequence wherein the 979th amino acid is threonine; the 1804th amino acid is leucine; and the 1966th amino acid is lysine. An HCV gene which can propagate in vitro and has higher replication efficiency and higher reinfection efficiency than the known HCV gene of genotype 1b was provided.