NOVELTY - An ethylene resin composition contains a modified material obtained by modifying ethylene polymer with radically polymerizable unsaturated compounds (B1,B2). Compound (B1) has ethylenic unsaturated silane compound. Compound (B2) has ethylenic unsaturated compound having hydroxyl, amino or epoxy groups, aromatic vinyl compound, unsaturated carboxylic acid, vinyl ester compound, vinyl chloride, and carbodiimide compound. Polymer has density of 900-940 kg/m3, melting peaks at 90-125 degrees C, melt flow rate of 0.1-100 g/10 minutes, and molecular weight distribution of 1.2-3.5.    USE - Ethylene resin composition is used for back surface-side solar cell sealing material for solar cell module e.g. thin-film solar cell module and crystal-form solar cell module (all claimed).    ADVANTAGE - The ethylene resin composition provides solar cell sealing material with excellent adhesiveness, electric insulation property, transparency, productivity, moldability and process stability. The solar cell module is economically manufactured using the sealing material with improved conversion efficiency and high moisture-permeability proof.    DETAILED DESCRIPTION - An ethylene resin composition contains a modified material obtained by modifying ethylene polymer with radically polymerizable unsaturated compounds (B1,B2). The compound (B1) consists of an ethylenic unsaturated silane compound. The compound (B2) has hydroxyl-containing ethylenic unsaturated compound, an amino-group containing ethylenic unsaturated compound, epoxy group-containing ethylenic unsaturated compound, an aromatic vinyl compound, unsaturated carboxylic acid or its derivative, vinyl ester compound, vinyl chloride, and carbodiimide compound. The ethylene polymer has density of 900-940 kg/m3, melting peaks at 90-125 degrees C by differential scanning calorimeter, melt flow rate of 0.1-100 g/10 minutes measured at 190 degrees C and load of 2.16 kg measured according to JIS K-6721, molecular weight distribution of 1.2-3.5 and metal residue content of 0.1-50 ppm.