NOVELTY - A sealing material sheet comprises 0.01-5 mass parts of light-resistant agent and less than or equal to 0.03 mass part of phenolic antioxidant with respect to 100 mass parts of cross-copolymer obtained by copolymerizing ethylene monomer, 10-35 mol.% aromatic vinyl compound monomer, and 0.01-0.2 mol.% aromatic polyene using single site coordination-polymerization catalyst to obtain ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer and polymerizing ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer and aromatic vinyl compound monomer using anionic initiator.    USE - A sealing material sheet for solar cell (claimed).    ADVANTAGE - Composition has excellent yellow discoloration property, transparency, soft property, light resistance, electric insulation, damp-proofness, and reliability.    DETAILED DESCRIPTION - A sealing material sheet comprises 0.01-5 mass parts of light-resistant agent and less than or equal to 0.03 mass part of phenolic antioxidant with respect to 100 mass parts of cross-copolymer obtained by copolymerizing ethylene monomer, 10-35 mol.% aromatic vinyl compound monomer, and 0.01-0.2 mol.% aromatic polyene using single site coordination-polymerization catalyst to obtain ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer and polymerizing ethylene-aromatic vinyl compound-aromatic polyene copolymer macromonomer and aromatic vinyl compound monomer using anionic initiator, wherein weight average molecular weight of the macromonomer is 3-150000 and molecular weight distribution (Mw/Mn) is 1.8-4, crystal melting heat ( Delta H) observed by 0-150 degrees C of the macromonomer is less than or equal to 30 J/g, relationship of TUS/DOU is 1.3-10, where TUS is total of polymerizable unsaturated group contained in the macromonomer and total of double bond+terminal double bond derived from divinylbenzene unit of the macromonomer and DOU is divinylbenzene unit content of the macromonomer, and mass ratio of the macronomer unit in cross-copolymer obtained through anion polymerization process is 40-90 mass%.