A method for producing an olefinic thermoplastic elastomer comprising mixing 100 parts by weight of an olefin copolymer rubber (A) obtained by polymerizing ethylene, an α-olefin having 3 to 20 carbon atoms and a non-conjugated polyene, and based on 100 parts by weight of the olefin copolymer rubber (A), 11 to 50 parts by weight of a volatile organic solvent (B) and 5 to 150 parts by weight of an olefin resin (C), and removing from the mixture the volatile organic solvent (B) while kneading in an extruder.