The present invention provides a resin composition containing: an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 mol % or more and 60 mol % or less; a polyamide resin (B); a carboxylic acid metal salt (C); and an unsaturated aldehyde (D), the mass ratio (A/B) of the ethylene-vinyl alcohol copolymer (A) to the polyamide resin (B) being 60/40 or more and 95/5 or less, the content of the carboxylic acid metal salt (C) with respect to a resin content in terms of a metal element equivalent being 1 ppm or more and 500 ppm or less, and the content of the unsaturated aldehyde (D) with respect to the resin content being 0.05 ppm or more and 50 ppm or less.