The present invention relates to 6-methylpyridine derivatives useful as an antiviral agent. More particularly, the present invention relates to novel 6-methylpyridine derivatives having an excellent inhibitory effect on replication of Hepatitis C virus (HCV), or pharmaceutically acceptable salts thereof, to a method for preparing thereof, and to an antiviral pharmaceutical composition comprising the compound as an active ingredient. The 6-methylpyridine derivatives of the present invention have an excellent inhibitory effect on replication of hepatitis C virus and thus can be advantageously used as a therapeutic or prophylactic agent of hepatitis C ##STR00001##