The polypropylene composition of the present invention comprises polypropylene and a rubber component, and has the following characteristics that(i) the melt flow rate (MFR: 230.degree. C., 2.16 kg load), as measured in accordance with ASTM D1238, is not less than 8 g/10 min,(ii) the flexural modulus (FM), as measured in accordance with ASTM D790, is not less than 20,000 kg/cm.sup.2,(iii) the Izod impact strength (IZ), as measured in accordance with ASTM D256, is not less than 20 kg.cm/cm,(iv) the heat deflection temperature (HDT), as measured in accordance with ASTM D648, is not lower than 135.degree. C.,(v) the dimensions of a polypropylene microcrystal in an injection molded article formed from the polypropylene composition, as measured by wide-angle X-ray diffractometry and small-angle X-ray scattering, are 5 nm-20 nm, 5 nm-20 nm and not less than 5 nm, respectively, in the directions of c-axis, a-axis and b-axis, and(vi) the rubber component is present in an injection molded article formed from the polypropylene composition as a continuous phase around the polypropylene microcrystal in the direction of injection and the direction perpendicular thereto, and the average thickness of this rubber continuous phase is in the range of from 0.5 nm-3 nm.Such a polypropylene composition as described above is excellent in rigidity and heat resistance, and also in impact resistance and toughness.