Direct nitridation of aluminum compacts (relative density 65%) consisting of commercial atomized powder was examined at temperatures from 500 to 700 degrees C, near or below the melting point of aluminum, and under a pressured nitrogen atmosphere between 0.5-7 MPa. Complete nitridation was achieved at a temperature as low as 540 degrees C by controlling the nitrogen pressure. The nitridation process and the structures of generated aluminum nitride (AIN) were drastically influenced by nitrogen pressure. Considering the relations between the reaction conditions and the reaction processes, it is suggested that low nitridation temperature and pre-heating in vacuum have a good effect on the nitridation ratio.