Mechanical and chemical treatments were found to improve the graphitization extent of graphitized platelet carbon nanofiber, which showed little change in graphitization parameters of X-ray diffraction even after heat treatment at 2800degreesC. Such treatments also restored the surface area that was significantly decreased through the formation of loop-shaped ends on the surface of carbon nanofibers by the graphitization. Formation, distortion, and removal of loop-shaped ends corresponded to such morphological and structural changes of the platelet carbon nanofiber. Relaxation of high-energy edges of the hexagon at the graphitization and high reactivity of closed loop ends at the treatments were observed under TEM. This study also supports existence of the primary rodlike structural unit in carbon nanofibers.