Aluminum nitride (AlN) was synthesized by carbothermal reduction and nitridation method from a mixture of various transition alumina powders and carbon black using 2.45 GHz microwave irradiation in N-2 atmosphere. We achieved the synthesis of AlN at 1300-1400 degrees C using 2.45 GHz microwave irradiation for 60 min. Our results suggest that -Al2O3 is more easily nitrided than -, -, and -Al2O3. On the other hand, nitridation ratio of samples synthesized in a conventional furnace under nitrogen atmosphere were zero or very low. These results show that 2.45 GHz microwave irradiation enhanced the reduction and nitridation reaction of alumina.