Provided is an adhesive which, in a metal foil-containing laminated composite film used in a high temperature sterilization treatment, is resistant to the effects of moisture in the air during curing, has good workability when used as a solvent-free adhesive, and exhibits excellent adhesive strength and acid resistance. Provided is a method for producing an adhesive composition, the method including: a step of obtaining an alcohol-added isocyanate (E) by reacting a trifunctional or higher isocyanate compound (C2) and a monofunctional alcohol (D) at an equivalence ratio of isocyanate groups in the trifunctional or higher isocyanate compound (C2):monofunctional alcohol (D)=100 mol %:25 to 65 mol %, and a step of mixing a polyisocyanate (A) containing a trifunctional or higher isocyanate compound (C1) and the alcohol-added isocyanate (E), and an alcohol (B) having an acid value of 0.5 to 30 mgKOH/g, so that the equivalence ratio between isocyanate groups in the polyisocyanate (A) and hydroxyl groups in the alcohol (B) (isocyanate groups/hydroxyl groups) is within a range from 0.7 to 2.5.