Ball-milling of graphite powder was performed by the use of a stainless steel ball-mill and an agate ball-mill. The crystal structure of the ground graphite was studied by transmission electron microscopy and X-ray diffractometry. A spectrometric approach to the change of structure during the milling process was also carried out by the carbon Kα X-ray-emission band spectroscopy (XES). The carbon Kα XES spectra were compared with those of carbon materials such as ball-milled diamond powder, i-diamond film and amorphous carbon powder. In the case of the stainless steel ball-milling, microcrystalline and/or onion-like structure were formed. The XES spectrum suggested that sp³ hybrid orbital was formed after 2000 h of milling. While, in the case of an agate ball-milling, it was suggested that the 2p orbital became narrow as a result of further finely-ground pulverization of graphite crystallite after 1750 h of milling.