This study proposes a sensorless decoupled current control method applied to Internal Permanent Magnet Synchronous Motor (IPMSM) drives via vector control and disturbance observer. The IPMSM presents the unavoidable and unmeasured disturbances, parameter variations and coupling between the axes. The coupling terms of the IPMSM are modeled as disturbances and these observed disturbances are used in the control law. Moreover, a model reference adaptive system with sliding mode technique is used to estimate the rotor speed. As result, a decoupled current control system and a sensorless rotor speed control are achieved. Experimental results are presented and they show the effectiveness of the proposed scheme.