The present invention relates to a therapeutic reagent for hepatitis C comprising HCV specific short interfering RNA (siRNA) as an effective ingredient. The siRNA of the invention is a double-stranded RNA specific for the nucleotide sequence of HCV which induces viral RNA degradation in mammalian cells and thereby inhibits HCV protein expression and replication. The method of the invention, which includes the step of administrating the synthetic siRNA or a DNA vector encoding the RNA, is thus effective for the treatment of HCV carrier by inhibiting HCV gene expression and replication.