PURPOSE: To provide a dynamically partially cured thermoplastic elastomer prepd. by compounding a propylene polymer material, an amorphous ethylene- propylene copolymer rubber, a semicrystalline low-density linear ethylene- propylene copolymer, etc., in specified amounts.

CONSTITUTION: 100 pts.wt. compsn. comprising 10-70 pts.wt. propylene polymer material (A) selected from among a crystalline polypropylene having an isotactic index of 90% or higher, etc., 20-60 pts.wt. amorphous ethylene-propylene copolymer rubber (B), and 10-30 pts.wt. semicrystalline low-density essentially linear ethylene-propylene copolymer (C) insoluble in xylene at room temp. is compounded with 3-15 pts.wt. 1,2-polybutadiene (D) and 0.5-3 pts.wt. peroxide crosslinker (E) having a half-life of 3.3-20 min at 160°C in EPDM.