PROBLEM TO BE SOLVED: To provide an olefin-based thermoplastic elastomer composition having excellent low-temperature rubber elasticity and comparable hardness to that of a conventional thermoplastic elastomer composition, and to provide a molded body thereof.SOLUTION: There is provided a thermoplastic elastomer composition which is obtained from 90 to 40 pts.et. of an ethylene-α-olefin-nonconjugated polyene copolymer and 10 to 60 pts.wt. of [II] a crystalline polyolefin resin, where the ethylene-α-olefin-nonconjugated polyene copolymer contains an ethylene [A], an α-olefin [B] having 3 to 20 carbon atoms, a non-conjugated polyene [C] containing one carbon-carbon unsaturated bond or one terminal carbon-carbon unsaturated bond in the molecule, and a structural unit derived from a non-conjugated polyene [D] containing two or more of the unsaturated bonds in total in the molecule, and which satisfies the following requirements (1) and (2) : (1) the molar ratio [A]/[B] between a structural unit
