NOVELTY - A heat sealing agent comprises urethane resin (A), polyolefin resin (B), crosslinking agent (C), and aqueous medium (D). The urethane resin is obtained by reacting urethane resin (a1) having an isocyanate group and compound (a2) having a primary amino group. The equivalent ratio of the primary amino group with respect to the isocyanate group is maintained at 1-2, during the reaction of urethane resin and compound (a2). The crosslinking agent comprises melamine compound, epoxy compound, oxazoline compound, carbodiimide compound, and/or isocyanate compound.    USE - Heat sealing agent is used for formation of laminated material used for manufacture of solar cell module (all claimed) used in motor vehicles, domestic electrical appliances, and solar power generation devices.    ADVANTAGE - The heat sealing agent has excellent adhesiveness and weather resistance, and provides the solar cell modules with excellent durability, heat resistance and moisture resistance, and high production efficiency.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) laminated material, which is obtained by forming a heat-sealing layer by coating the heat sealing agent on the surface of polar group material, drying, mounting a non-polar base material on the surface of the heat-sealing layer, and heating at 80-180 degrees C;    (2) formation of laminated material, which involves carrying out self-crosslinking reaction of the alkylated methylol melamine resin with the functional group contained in the urethane resin and/or polyolefin resin and the epoxy group contained in the epoxy compound, and/or reacting the alkylated methylol melamine resin with the hydroxyl group generated by the reaction of the epoxy compound and the functional group;    (3) solar cell module, which consists of solar cell, laminated material having heat-sealing layer, and back sheet layer. The heat-sealing layer is formed on the surface of non-polar base material containing ethylene-vinyl acetate copolymer, with respect to light-receiving surface of the solar cell. The back sheet layer contains the polar group material, which is chosen from polyethylene-terephthalate base material, polypropylene base material, polycarbonate base material, and polyamide base material; and    (4) manufacture of solar cell module.