Provided are a resin composition for solar cell encapsulant which contains an ethylene/α-olefin and is satisfactory in terms of crosslinkability, heat resistance, transparency, and impact resistance, a solar cell encapsulant formed from the resin composition, and a solar cell module obtained using the resin composition. Provided are a resin composition for solar cell encapsulant and the likes, which comprises an ethylene/α-olefin copolymer (A) having the following properties (a1) to (a3) and organic peroxide (B): (a1) a branch number derived from comonomer (N) and a total number of vinyl and vinylidene (V) in the ethylene/α-olefin copolymer satisfy the following relationship of expression (1): N×V≧10, wherein N and V are the number, as determined by NMR, per total of 1,000 carbon atoms contained in the main chain and side chain, (a2) an MFR (190° C., 21.18-N load) is 0.1-100 g/10 min, and (a3) a density is 0.860-0.920 g/cm3.