A thermoplastic resin composition comprising a matrix phase that comprises an ethylene-vinyl alcohol copolymer, and a dispersed phase that comprises a brominated isobutylene-p-methylstyrene copolymer and an acid-modified styrene-ethylene-butylene-styrene copolymer, wherein the thermoplastic resin composition satisfies the following formula: 0.02 ≤ W B × B B × W C × S C / W A × V A ≤ 0.85 wherein WA represents the weight ratio of the ethylene-vinyl alcohol copolymer to the total weight of polymer components in the thermoplastic resin composition, W B represents the weight ratio of the brominated isobutylene- p -methylstyrene copolymer to the total weight of polymer components in the thermoplastic resin composition, W C represents the weight ratio of the acid-modified styrene-ethylene-butylene-styrene copolymer to the total weight of polymer components in the thermoplastic resin composition, V A represents the vinyl alcohol content (% by weight) in the ethylene-vinyl alcohol copolymer, B B represents the p -bromomethylstyrene content (% by weight) in the brominated isobutylene-p-methylstyrene copolymer, and S C represents the styrene content (% by weight) in the acid-modified styrene-ethylene-butylene-styrene copolymer. a matrix phase that comprises an ethylene-vinyl alcohol copolymer, and a dispersed phase that comprises a brominated isobutylene-p-methylstyrene copolymer and an acid-modified styrene-ethylene-butylene-styrene copolymer, wherein the thermoplastic resin composition satisfies the following formula: 0.02 ≤ W B × B B × W C × S C / W A × V A ≤ 0.85 wherein WA represents the weight ratio of the ethylene-vinyl alcohol copolymer to the total weight of polymer components in the thermoplastic resin composition, W B represents the weight ratio of the brominated isobutylene- p -methylstyrene copolymer to the total weight of polymer components in the thermoplastic resin composition, W C represents the weight ratio of the acid-modified styrene-ethylene-butylene-styrene copolymer to the total weight of polymer components in the thermoplastic resin composition, V A represents the vinyl alcohol content (% by weight) in the ethylene-vinyl alcohol copolymer, B B represents the p -bromomethylstyrene content (% by weight) in the brominated isobutylene-p-methylstyrene copolymer, and S C represents the styrene content (% by weight) in the acid-modified styrene-ethylene-butylene-styrene copolymer. WA represents the weight ratio of the ethylene-vinyl alcohol copolymer to the total weight of polymer components in the thermoplastic resin composition, W B represents the weight ratio of the brominated isobutylene- p -methylstyrene copolymer to the total weight of polymer components in the thermoplastic resin composition, W C represents the weight ratio of the acid-modified styrene-ethylene-butylene-styrene copolymer to the total weight of polymer components in the thermoplastic resin composition, V A represents the vinyl alcohol content (% by weight) in the ethylene-vinyl alcohol copolymer, B B represents the p -bromomethylstyrene content (% by weight) in the brominated isobutylene-p-methylstyrene copolymer, and S C represents the styrene content (% by weight) in the acid-modified styrene-ethylene-butylene-styrene copolymer.