This paper proposes a novel method of velocity measurement for motor drives with optical encoders. Acceleration control is indispensable for advanced motion control while it requires accurate velocity information. Although many methods on velocity measurement have been proposed, accurate measurement was not achieved in a high-speed range. We therefore propose " synchronousmeasurement method (S method)" that measures the velocity synchronized with alteration of pulse numbers. Accurate velocity measurement is achieved in all speed ranges with this method. Furthermore, other estimation methods are applicable in addition since the method does not require any model of a control object. Simulation and experimental results verify the validity of the proposed method.