There is provided an encapsulant material for solar cells which facilitates production of a solar cell module and is excellent in flexibility, heat resistance, transparency, etc., and a solar cell module produced using the encapsulant material. The present invention relates to an encapsulant material for solar cells which includes a resin composition (C) containing an ethylene-α-olefin random copolymer (A) capable of satisfying the following condition (a) and an ethylene-α-olefin block copolymer (B) capable of satisfying the following condition (b): (a) a heat of crystal fusion is from 0 to 70 J/g as measured in differential scanning calorimetry at a heating rate of 10° C./min; and (b) a crystal fusion peak temperature is 100° C. or higher and a heat of crystal fusion is from 5 to 70 J/g as measured in differential scanning calorimetry at a heating rate of 10° C./min.