The present invention provides an amine based epoxy resin curing agent and an epoxy resin composition containing the curing agent. The epoxy resin composition has a high gas barrier performance, a long pot life, and utility as a coating material or an adhesive for laminates. The amine based epoxy resin curing agent is composed of a reaction product of (A), (B) and (D) or (A), (B), (C) and (D): (A) m-xylylenediamine or p-xylylenediamine; (B) a polyfunctional compound having at least one acyl group, which is capable of forming an amide group site through a reaction with a polyamine and forming an oligomer; (C) a monovalent carboxylic acid having from 1 to 8 carbon atoms and/or its derivative; and (D) a functional compound having at least one carbonate site represented by the formula (2), which is capable of forming a carbamate site represented by the formula (1) through a reaction with a polyamine: