The morphology and mechanical properties of novel block copolymers consisting of isotactic polypropylene (PP) and ethylene-propylene rubber (EPR) synthesized by a short-period polymerization method were examined using differential scanning calorimetry, atomic force microscopy, dynamic mechanical analysis, and a rheooptical technique. It was found that the novel block copolymers show a single glass transition and EPR segments are trapped into the amorphous region of PP. Furthermore, the rheooptical analysis demonstrates that a drawing process of the EPR-rich block copolymer induces orientation of the PP lamellae in the EPR matrix.