Disclosed is a resin composition forming an adhesive layer between a polylactic acid resin substrate layer and a polyolefin resin substrate layer. The resin composition includes a modified polyolefin resin (A) and a terpene resin (B), and the mass ratio (A)/(B) between the both resins (A) and (B) is 20/80 to 99/1. Alternatively, the resin composition may be a resin composition including 10 to 90% by mass of a polylactic acid resin (C), 5 to 89% by mass of the modified polyolefin resin (A) and 1 to 80% by mass of a hydrogenated petroleum resin (D), with the total amount of these resins constrained to be 100% by mass.