A method of producing a laminate comprising a heat treatment step under a temperature condition of 80-140° C. for 5-120 minutes, wherein the laminate satisfies the following requirements: (1) an adhesive layer (I) with 97-70% by weight of a propylene copolymer (A) and 3-30% by weight of a copolymer (B) having a structural unit derived from butane (100% by weight); (2) the copolymer (A) has a melting point within a specific range and includes less than 1 mol % of structural unit from butane; (3) the copolymer (B) has a melting point within a specific range and includes 1 mol % or more of structural unit from butane; (4) the adhesive layer (I) has a polymer (C) with a structural unit from at least one graft monomer selected unsaturated carboxylic acids and derivatives thereof, and, (5) a substrate layer (II) includes a polyester resin.