PURPOSE: The titled thermoforming composition excellent in melt tension, low- temperature impact resistance, etc., prepared by mixing crystalline polypropylene with medium-density and high-density polyethylenes and an amorphous ethylene/ propylene copolymer in a specified weight ratio.

CONSTITUTION: The purpose thermoforming polypropylene composition is prepared by mixing (A) 92W60wt% crystalline polypropylene, density of 0.89W0.93g/ cm2 and melt index of 0.1W10g/10min, with (B) 3W15wt% medium-density polyethylene, density of 0.93W0.945g/cm3 and melt index of 0.2W5g/10min, (C) 2W 10wt% high-density polyethylene, density of 0.945W0.965g/cm3 and melt index of 0.2W5g/10min, and (D) 3W15wt% amorphous ethylene/propylene copolymer, in amounts such that the sum of components B, C and D accounts for 8W40wt%.