The invention provides a sealing material for caps, e.g., metal caps for food containers, which is reduced in swelling with substances dissolved out or alcoholic beverages and in adsorption of the odor thereof and which comprises a tough and nonyellowing polyurethane elastomer and has satisfactory sealing performance. and to provide a manufacturing method for the lid using the sealing material. The sealing material is made of the polyurethane elastomer that is given by reacting the following elements (A), (B), (C), where (A) is a polyisocyanate element which is given by modifying an aliphatic isocyanate and / or an alicyclic isocyanate, contains isocyanate groups of 5 to 38 mass%, and shows an average functional group number of 2 to 3, (B) is a polyol element which has a hydroxyl group value of 20 to 350 (mgKOH / g) and shows an average functional group number of 2 to 3, and (C) is a fatty acid glycerol ester having hydroxyl groups.