A composition for coating having a gas barrier property comprising coating-forming components of an epoxy resin and an amine curing agent, wherein said amine curing agent is a reaction product of (A) methaxylylenediamine or paraxylylenediamineand (B) polyfunctional compound having at least one acyl group which is capable of forming amide group moiety by reaction with a polyamine to form an oligomeror or (A), (B) and (C)monocarboxylic acid having 1 to 8 carbon atoms and/or derivative thereof and a coating and a coated film a gas barrier property the same.