A resin composition contains a polyolefin-based resin (A), a polyvinyl alcohol-based resin (B), and acetic acid (C), and a content of the acetic acid (C) is 60 mass ppm or greater. The polyolefin-based resin (A) may contain polyethylene or polypropylene. The polyvinyl alcohol-based resin (B) may contain a modified polyvinyl alcohol-based resin. The resin composition may further contain an acid-modified polyolefin-based resin (D). The content of the acetic acid (C) may be 200 mass ppm or less.