NOVELTY - An ethylene-vinyl acetate copolymer composition comprises ethylene-vinyl acetate copolymer as main structural component. The content rate of vinyl acetate unit in ethylene-vinyl acetate copolymer is 25-33 %mass. The storage elastic modulus (E1) of ethylene-vinyl acetate copolymer composition at 90-110 degrees C strain rate of 0.1 s-1 satisfies specific relation (I). The storage elastic modulus (E2) of ethylene-vinyl acetate copolymer composition at 90-110 degrees C and strain rate of 1 s-1 satisfies specific relation (II).    USE - Ethylene-vinyl acetate copolymer composition comprises is used for manufacturing solar cell sealing material sheet (all claimed) for solar cell module.    ADVANTAGE - The solar cell sealing material sheet formed using ethylene-vinyl acetate copolymer composition has excellent external appearance and crack resistance with reduced residual distortion, and is efficient.    DETAILED DESCRIPTION - An ethylene-vinyl acetate copolymer composition comprises ethylene-vinyl acetate copolymer as main structural component. The content rate of vinyl acetate unit in ethylene-vinyl acetate copolymer is 25-33 %mass. The storage elastic modulus (E1) of ethylene-vinyl acetate copolymer composition at 90-110 degrees C strain rate of 0.1 s-1 satisfies a relation: 1.05asterisk105+a less than or equal to E1 greater than or equal to 1.25asterisk105+b, where a is (-6.31asterisk(T-110))/(312.58+(T-110)) and b is (-6.78asterisk(T-110))/(353.88+(T-110)) (I). The storage elastic modulus (E2) of ethylene-vinyl acetate copolymer composition at 90-110 degrees C and strain rate of 1 s-1 satisfies a relation: 3.5asterisk104+a less than or equal to E2 greater than or equal to 4asterisk104+b (II). INDEPENDENT CLAIMS are included for the following:    (1) manufacture of solar cell sealing material sheet, which involves carrying out melt extrusion ethylene-vinyl acetate copolymer composition, and molding in a sheet form; and    (2) solar cell sealing material sheet.