A thermoplastic elastomer composition comprising the following components [A], [B], [C], and [D]: [A] 5 to 60 mass % of an ethylene-α-olefin-based copolymer having a limiting viscosity of 3.5 dl/g or more measured in a decalin solvent at 135° C., [B] 1 to 20 mass % of a polyolefin-based resin, and [C] 30 to 94 mass % of a mineral oil-based softening agent, provided that the total of the components [A], [B], and [C] is 100 mass %, and for 100 parts by mass of the components [A], [B], and [C], [D] 0.1 to 50 parts by mass of a hydrogenated diene-based polymer, at least [A] the ethylene-α-olefin-based copolymer and [B] the polyolefin-based resin being dynamically treated with heat in the presence of a cross-linking agent, or the above thermoplastic elastomer composition wherein [A] is replaced with an oil-extended rubber comprising [A1] 20 to 80 mass % of an ethylene-α-olefin-based copolymer having a limiting viscosity of 3.5 dl/g or more measured in a decalin solvent at 135° C. and [C1] 20 to 80 mass % of a mineral oil-based softening agent, provided that the total of [A1] and [C1] is 100 mass %. This thermoplastic elastomer composition excels in molding processability, has low hardness, is free from bleed-out of a mineral oil-based softening agent, has high flexibility and superior rubber elasticity (rebound resilience and compression set), and excels in recycling efficiency.