Abstract: A process for preparing a propylene polymer composition comprising conducting multistage polymerization including a step (a) for preparing a propylene (co)polymer (a) and a step (b) for preparing an ethylene copolymer (b) in the presence of (A) a transition metal compound and (B) a compound activating the transition metal compound (A), in which the steps (a) and (b) may be carried out in any order, and the resulting propylene polymer composition contains the propylene (co)polymer (a) in an amount of 20 to 90% by weight and the ethylene copolymer (b) in an amount of 10 to 80% by weight and has MFR, as measured at 230.degree. C. under a load of 2.16 kg, of 0.01 to 500 g/10 min; and a propylene polymer composition prepared by this process. The process according to the invention can prepare a propylene polymer composition having excellent rigidity, heat resistance and impact resistance.