A resin composition comprising from 50 to 95% by weight of a modified ethylene-vinyl alcohol copolymer that contains from 0.3 to 40 mol% of a structural unit provided below and has an ethylene content of from 5 to 55 mol%, and from 5 to 50% by weight of a soft resin that is a thermoplastic elastomer selected from the group consisting of styrene-based elastomers, polyurethane-based elastomers, polyester-based elastomers and polyether-based elastomers, or an olefin-based copolymer selected from the group consisting of ethylene-propylene copolymers, VLDPE and linear low density polyethylene (LLDPE), wherein the soft resin has at least one functional group able to react with a hydroxyl group selected from the group consisting of a carboxyl group including groups composed of carboxylic anhydride, an epoxy group and boron-containing groups, and has a Young's modulus at 23°C, 50% RH calculated from the initial inclination of an stress-strain curve measured in a thermostatic chamber at 23°C and 50% RH of a 15 mm wide strip-shaped section of a 20 μm thick monolayer film made by a twin screw extruder manufactured by Toyo Seiki Seisaku-Sho, Ltd. under conditions of a chuck span of 50 mm and a tensile speed of 50 mm/min using an "Autograph (Model AG-A500)" manufactured by Shimadzu Corp. of 500 MPa or less, wherein the soft resin is dispersed with an average particle diameter of 0.1 μm or less in a matrix of the modified ethylene-vinyl alcohol copolymer, wherein the resin composition has an oxygen transmission rate at 20°C and 65% RH measured by use of an OXTRAN 2/20A manufactured by Modern Control, Inc. of a multilayer film prepared by dry lamination of a 50 μm thick CPP film to a 20 μm thick monolayer film made by a twin screw extruder manufactured by Toyo Seiki Seisaku-Sho, Ltd. using an adhesive AD-335A produced by Toyo-Morton, Ltd. of not more than 100 cc·20μm/m 2 ·day·atm, wherein the degree of saponification of the vinyl ester component in an ethylene-vinyl alcohol copolymer used as raw material of the modified ethylene-vinyl alcohol copolymer is not less than 90%, and wherein the ethylene-vinyl alcohol copolymer has an intrinsic viscosity of not less than 0.06 L/g: wherein R 1, R 2, R 3 and R 4 denote a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms; R 1, R 2, R 3 and R 4 may be the same group or may differ; R 3 and R 4 may be combined together; and R 1, R 2, R 3 and R 4 each may have a hydroxyl group, a carboxyl group or a halogen atom. wherein the soft resin has at least one functional group able to react with a hydroxyl group selected from the group consisting of a carboxyl group including groups composed of carboxylic anhydride, an epoxy group and boron-containing groups, and has a Young's modulus at 23°C, 50% RH calculated from the initial inclination of an stress-strain curve measured in a thermostatic chamber at 23°C and 50% RH of a 15 mm wide strip-shaped section of a 20 μm thick monolayer film made by a twin screw extruder manufactured by Toyo Seiki Seisaku-Sho, Ltd. under conditions of a chuck span of 50 mm and a tensile speed of 50 mm/min using an "Autograph (Model AG-A500)" manufactured by Shimadzu Corp. of 500 MPa or less, wherein the soft resin is dispersed with an average particle diameter of 0.1 μm or less in a matrix of the modified ethylene-vinyl alcohol copolymer, wherein the resin composition has an oxygen transmission rate at 20°C and 65% RH measured by use of an OXTRAN 2/20A manufactured by Modern Control, Inc. of a multilayer film prepared by dry lamination of a 50 μm thick CPP film to a 20 μm thick monolayer film made by a twin screw extruder manufactured by Toyo Seiki Seisaku-Sho, Ltd. using an adhesive AD-335A produced by Toyo-Morton, Ltd. of not more than 100 cc·20μm/m 2 ·day·atm, wherein the degree of saponification of the vinyl ester component in an ethylene-vinyl alcohol copolymer used as raw material of the modified ethylene-vinyl alcohol copolymer is not less than 90%, and wherein the ethylene-vinyl alcohol copolymer has an intrinsic viscosity of not less than 0.06 L/g: wherein R 1, R 2, R 3 and R 4 denote a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms; R 1, R 2, R 3 and R 4 may be the same group or may differ; R 3 and R 4 may be combined together; and R 1, R 2, R 3 and R 4 each may have a hydroxyl group, a carboxyl group or a halogen atom.