Morphological change of a large pore was evaluated for the final stage of densification in alumina ceramics. Specimens prepared at various sintering temperatures were ground to a thickness of 150 μm The internal structures of the sintered specimens were examined with an optical microscope in transmission mode to determine the location of large pores. Detailed structures of the large pores were evaluated by scanning electron microscopy after expostion on the surface by polishing. The large pores have a crack-like shape in the specimens sintered at 1350°C. Over sintered specimens maintained large porosity area consisting of many small pores.