NOVELTY - The composition comprises dispersion medium and metallic nanoparticles dispersed in the dispersion medium. The metallic nanoparticles comprise 75 wt.% or more silver nanoparticles and are chemically modified with protective agent whose carbon skeleton comprises 1-3C organic molecule principal chain. The metallic nanoparticles comprise metallic nanoparticles having primary particle diameter of 10-50 nm, in proportional 70% or more by number average.    USE - Composition for forming electrode of solar cell (both claimed).    ADVANTAGE - The electrode containing the composition provides solar cell having excellent durability, high conductivity and high reflectance.    DETAILED DESCRIPTION - The composition comprises dispersion medium and metallic nanoparticles dispersed in the dispersion medium. The metallic nanoparticles comprise 75 wt.% or more silver nanoparticles and are chemically modified with protective agent whose carbon skeleton comprises 1-3C organic molecule principal chain. The metallic nanoparticles comprise metallic nanoparticles having primary particle diameter of 10-50 nm, in proportional 70% or more by number average. The dispersion medium contains water (1 wt.% or more) and alcohol (2 wt.% or more). The dispersion medium contains hydroxyl group and/or carbonyl group. The metal nanoparticles consist of mixed composition or alloy composition consisting of gold, platinum, palladium, ruthenium, nickel, copper, tin, indium, zinc, iron, chromium and/or manganese. The alcohol is methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, isobornyl hexanol, glycerol and/or erythritol. The composition further contains metal soap, metal oxide, metal hydroxide, organometallic compound and/or silicone oil. The metal oxide is oxide or complex oxide of aluminum, silicon, titanium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium and/or antimony. The metal hydroxide is hydroxide of aluminum, silicon, titanium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin, indium and/or antimony. The organometallic compound is metal soap, metal complex or metal alkoxide of silicon, titanium, chromium, manganese, iron, cobalt, nickel, silver, copper, zinc, molybdenum, tin and/or indium. The composition is coated on base material chosen from transparent electroconductive material, polymeric material, or ceramic containing silicon, glass or metal. The base material is subjected to priming process using coating material containing silver, copper, tin, palladium, zinc, nickel, molybdenum, chromium, manganese, aluminum, zirconium, titanium, ruthenium, platinum, indium and/or silicon, resin(s) chosen from isocyanate component, polyester component and polyether component, alkoxide(s), one type or two or more types of metal soap and coupling agent(s).