In a conventional speed sensorless stator flux-oriented (SFO) induction motor drive, when the estimated speed is transformed into the sample-data model using the first-forward difference approximation, the sampled data model has a modeling error which, in turn, produces an error in the rotor speed estimation. The error is removed by the use of a low pass filter (LPF). As a result, the delay of the estimated speed occurs in transients by the use of the LPF. This paper proposes a method to estimate exactly the speed by using Luenberger observer to solve the problem of a conventional method.