Strain-induced AZ91D magnesium alloy bulk was semi-solid press-formed. Microstructure and mechanical properties of the formed specimen were investigated. By using strain-induced bulk, a microstructure is able to be obtained in which fine and nearly spherical magnesium solid solution distributes uniformly. Furthermore, the eutectic phase becomes finer by rapid cooling. The tensile properties of the press-formed specimen are sufficiently superior to those specified in JIS. Particularly, 0.2% proof strength of the formed specimen remarkably surpasses that of JIS specification due to the formation of fine eutectic phase. Since the eutectic phase is the initiation of fracture, however, the mechanical properties are greatly influenced by the quantity and distribution of eutectic phase. For instanse, ductility of formed specimen is considerably small because of the existence of continuous eutectic phase at grain boundaries. Nevertheless tensile properties could possibly be improved (better than JIS specification) owing to disappearance of the eutectic phase by T4 or T6 treatment.