A propylene resin composition obtained by dynamic heat treatment of a blend of (A) 100 parts by weight of a propylene-.alpha.-olefin block copolymer wherein a ratio (.eta..sub.1 /.eta..sub.2) of melt viscosity .eta..sub.1 at a shear rate of 10.sup.1 sec.sup.-1 to melt viscosity .eta..sub.2 at a shear rate of 10.sup.2 sec.sup.-1 is 3.5 to 8 as measured by a slit die method and (B)0.005 to 2 parts by weight of an organic peroxide, and having a melt flow rate (measured according to JIS K7210, at a temperature of 230.degree. C. under a load of 2.16 kg) adjusted to 50 to 300 g/10 minutes, a main endothermic peak temperature Tmp of 120.degree. to 150.degree. C. for melting temperature and a main exothermic peak temperature Tcp of 85.degree. to 105.degree. C. for crystallization temperature, as measured with a Differential Scanning Calorimetry, and a Tcp half-value width of 5.degree. C. or above, and a molded article obtained by using the same.