Effect of high molecular weight component (HMwPLLA) on the crystallization on PLLA under shear flow has been investigated by means of small-angle X-ray scattering and light scattering. As for crystallization under applied shear condition, PLLA/10%-HMwPLLA was for times faster than homo-PLLA. Oriented Kebab structure was observed at the early stage of crystallization for the blend sample, possibly due to the pre-formation of shish structure, while no anisotropic crystallization was observed for homo-PLLA. The critical concentration of HMwPLLA for the shish-kebab structure formation was estimated at around 0.3wt%, which shows good agreement with that for chain entanglement between high molecular weight PLLA. It indicates that the entanglement between HMwPLLA plays an important role for the formation of shish structure, kebab orientation, and the acceleration of crystallization.