Efficient and precise sensorless speed control of Permanent Magnet Synchronous Motor (PMSM) requires accurate knowledge of rotor flux position and speed. In the present paper, an indirect rotor flux oriented scheme for sensorless speed control of PMSM is proposed in which the rotor flux position is estimated by direct integration of the estimated rotor speed to reduce the effect of system noise. The rotor flux magnitude and the rotor flux speed are estimated adaptively using stable Model Reference Adaptive System (MRAS) estimators. Simple stability analysis and design of the estimators are performed using linear control theory. The convergence of rotor position and speed estimation errors to zero is guaranteed. Simulation and experimental results obtained show excellent performance.