This paper presents the sliding mode position controller for induction machine drives based on the passivity theorem. Firstly, a current model rotor flux observer estimates the flux, and then the designed adaptive laws are employed to estimate the inverse rotor time constant and the load torque. Therefore, the bothersome chattering phenomenon of a conventional sliding mode controller can be reduced. The stability analysis of the feedback connection of the observer and the estimator, and the position controller is carried out by using the passivity approach. The overall system is proved to be asymptotically stable. Finally, experimental results show that the proposed controller is robust to the variations of the motor mechanical parameters, external load torque disturbances, and the inverse rotor time constant. Furthermore, the controller has good capability of tracking a square waveform command.