This paper proposes a high efficiency Switched Reluctance Motor (SRM) driving method using a Current Source Inverter (CSI). Usually the SRM is driven by a Voltage Source Inverter (VSI) and the torque is controlled by a current hysteresis control. However, disadvantages of these drives are that the current rising time is slow and the large current ripple is caused because of the large and non-linear inductance which generate large back-EMF. On the other hand, the CSI drive for SRM has some advantages that fast di/dt is realized and the constant current can be added in the period of the inductance increases. In this paper, a CSI for SRM drive is described and the efficiency of the motor and the inverter are measured. Consequently, the efficiency of the whole motor drive system is improved 2% by the proposed SRM drive technique in comparison with the conventional SRM drive. Further, by using the speed changeable gate drive circuit, the surge voltage of the CSI is reduced.