PROBLEM TO BE SOLVED: To provide a compound that is effective in inhibiting the function of non-structural protein NS5A which is an essential component in the replication of C type hepatitis virus ("HCV").SOLUTION: Provided is a compound exemplified by methyl{(2S,3R)-1-[(2S)-2-{5-[(2R,5R)-1-{3,5-difluoro-4-[4-(4-fluorophenyl)piperidine-1-yl]phenyl}-5-(6-fluoro-2-{(2S)-1-[N-(methoxycarbonyl)-O-methyl-L-threonyl]pyrrolidin-2-yl}-1H-benzimidazole-5-yl) pyrrolidin-2-yl]-6-fluoro-1H-benzimidazole-2-yl}pyrrolidin-1-yl]-3-methoxy-1-oxobutanoic-2-yl}carbamate or the like, or a pharmaceutically acceptable salt thereof and a derivative thereof.SELECTED DRAWING: None
