A thermoplastic elastomer composition having superior moldability and appearance, and low anisotropy of mechanical properties, especially, tensile strength, and retaining low temperature impact strength, is obtained by melt-kneading an intermediate composition comprising (a) 100 parts by weight of a selectively hydrogenated block copolymer which has at least two mono-alkenyl or mono-­alkenylidene aromatic hydrocarbon polymer blocks A having a number-average molecular weight of 25,000 - 35,000 and at least one partially or completely hydrogenated aliphatic conjugated diene hydrocarbon polymer block B having a number-average molecular weight of 100,000 - 150,000, (b) 50 - 150 parts by weight of an extender oil and (c) 0 - 50 parts by weight of polypropylene I, then adding, to the kneaded intermediate composition, (d) polypropylene II contain­ing at least 35 % by weight of a propylene-ethylene block copolymer having a melt flow rate of 10 - 30 g/10 min. and an ethylene content of 3 - 15 % by weight in such amount that total amount of polypropylene I plus polypropylene II is 200 - 400 parts by weight per 100 parts by weight of block copolymer (a) and then further melt kneading the mixture. Further addition of a filler to the composition can afford a thermoplastic elastomer composition of small linear expansion coefficient while retaining the above properties.