NOVELTY - A sealing material is obtained by resin composition containing light-resistant agent and cross-copolymer obtained by performing coordination polymerization and anion polymerization. An ethylene monomer, aromatic vinyl compound monomer and aromatic polyene are coordination-polymerized using catalyst to obtain ethylene-aromatic vinyl compound-polyene copolymer macromonomer. The obtained ethylene-aromatic vinyl compound-polyene copolymer macromonomer and aromatic vinyl compound monomer are anion-polymerized in presence of anionic initiator to obtain cross-copolymer.    USE - Sealing material is used for solar cell (claimed).    ADVANTAGE - The sealing material has excellent transparency, soft property, light resistance and reliability.    DETAILED DESCRIPTION - A sealing material is obtained by resin composition containing 0.5-5 parts mass of light-resistant agent and cross-copolymer obtained by performing coordination polymerization and anion polymerization. An ethylene monomer, aromatic vinyl compound monomer and aromatic polyene are coordination-polymerized using single-site coordination polymerization catalyst to obtain ethylene-aromatic vinyl compound-polyene copolymer macromonomer. The obtained ethylene-aromatic vinyl compound-polyene copolymer macromonomer and aromatic vinyl compound monomer are anion-polymerized in presence of anionic initiator to obtain cross-copolymer. The amount of aromatic vinyl compound unit in the cross-copolymer is 10-35 mol%. The amount of aromatic polyene in the cross-copolymer is 0.01-0.2 mol%. The ethylene-aromatic vinyl compound-polyene copolymer macromonomer obtained by coordination polymerization has weight average molecular weight of 3-150000, molecular weight distribution of 1.8-3 and crystallization heat of fusion (( Delta )H) of 30 J/g or less at 0-150 degrees C. The ratio (TUS/DOU) of ethylene-aromatic vinyl compound-polyene copolymer macromonomer is 1.3-10. TUS is the total polymerizable unsaturated group contained in ethylene-aromatic vinyl compound-polyene copolymer macromonomer with respect to total of double bond and terminal bond in divinyl benzene unit of ethylene-aromatic vinyl compound-polyene copolymer macromonomer. DOU is the content of divinyl benzene unit in the ethylene-aromatic vinyl compound-polyene copolymer macromonomer. The amount of ethylene-aromatic vinyl compound-polyene copolymer macromonomer in the cross-copolymer obtained by anion polymerization is 40-90 %mass.