A production process of a propylene block copolymer, comprising the steps of (I) contacting a solid catalyst component containing titanium atoms, magnesium atoms and halogen atoms with an organoaluminum compound and an external electron donor represented by the defined formula, thereby forming a polymerization catalyst, (II) polymerizing propylene in the presence of the polymerization catalyst, thereby forming a polymer component (1) having an intrinsic viscosity, [η]1, and (III) copolymerizing propylene with an olefin other than propylene in the presence of the polymer component (1), thereby forming a polymer component (2) having an intrinsic viscosity, [η]2, which is three times or more [η]1.