NOVELTY - A polyurethane adhesive contains a main component comprising (in wt.%) polyester polyol (A) (40-70) having number average molecular weight of 10000-50000, polycarbonate polyurethane polyol (B) (15-35) and bisphenol-type epoxy resin (C) (15-35), and a hardening agent containing polyisocyanate component (D) (50-100) having isocyanurate structure. The polyol (B) contains 50-100 mol% of polycarbonate polyol, and has number average molecular weight of 10000-30000 and urethane bond equivalent of 1000-2500. The epoxy resin has number average molecular weight of less than 1000.    USE - Polyurethane adhesive is used as adhesive agent for back surface protection sheet of solar cell (all claimed).    ADVANTAGE - The polyurethane adhesive has excellent adhesive strength, heat resistance, moisture resistance, delamination resistance and deterioration resistance.    DETAILED DESCRIPTION - A polyurethane adhesive contains a main component comprising (in wt.%) polyester polyol (A) (40-70) having number average molecular weight of 10000-50000, polycarbonate polyurethane polyol (B) (15-35) and bisphenol-type epoxy resin (C) (15-35), and a hardening agent containing polyisocyanate component (D) (50-100) having isocyanurate structure. The polyester polyol (A) contains 20-60 mol% of aromatic dibasic acid component and 40-80 mol% of 9C or more aliphatic dibasic acid component as dibasic acid component, and 20-100 mol% of 5C or more aliphatic polyhydric alcohol as polyhydric alcohol component. The polyol (B) contains 50-100 mol% of polycarbonate polyol with respect to 100 mol% of polyol component, and has number average molecular weight of 10000-30000 and urethane bond equivalent of 1000-2500. The epoxy resin has number average molecular weight of less than 1000. An INDEPENDENT CLAIM is included for back surface protection sheet (5a) for solar cell, which has an adhesive layer (51) formed using polyurethane adhesive as adhesive agent, provided between sheet-like components (11,12) of a laminate.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view of the solar cell.    Back surface protection sheet (5a)    Sheet-like components (11,12)    Plastic film (21)    Vapor deposition layer (22)    Adhesive layer (51)