NOVELTY - A sealing material resin contains a cross-copolymer obtained by copolymerizing ethylene monomer, aromatic vinyl compound monomer and aromatic polyene using single-site coordination polymerization catalyst, and polymerizing ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer and aromatic vinyl compound monomer using anionic initiator. The macromonomer has weight average molecular weight of 30000-150000, molecular weight distribution of 1.8-4, and crystal melting heat of 30 J/g or less at 0-150 degrees C. Mass ratio of macromonomer unit in cross-copolymer is 75-95 %mass.    USE - Sealing material resin is used for sealing material sheet for solar cell (all claimed).    ADVANTAGE - The sealing material resin has excellent mechanical properties, transparency, heat resistance, electrical insulation properties, damp-proofing properties, softness and sealing properties.    DETAILED DESCRIPTION - A sealing material resin contains a cross-copolymer obtained by copolymerizing ethylene monomer, an aromatic vinyl compound monomer and aromatic polyene using a single-site coordination polymerization catalyst, obtaining ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer containing aromatic vinyl compound unit (17-30 mol%), aromatic polyene unit (0.01-0.2 mol%) and ethylene unit (remaining), reacting obtained macromonomer and an aromatic vinyl compound monomer, and polymerizing using an anionic initiator. The macromonomer has weight average molecular weight of 30000-150000, molecular weight distribution of 1.8-4, and crystal melting heat of 30 J/g or less at 0-150 degrees C. The mass ratio of macromonomer unit in cross-copolymer is 75-95 %mass.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view of solar cell.    Light receiving surface side transparent protection component (A)    Back surface side protection component (B)    Light receiving surface side sealing material (C1)    Back surface side sealing material (C2)    Cell (D)