Majority of the electricity used in the industry is consumed by induction motors. Early detection of abnormal cases that occur at the electrical and mechanical parts of these motors is very important for the safe operation of industrial facilities and the decrease of economic losses. In this presented study, the detection of parallel, angular and mixed misalignment fault in inverter fed induction motors has been carried out via the harmonic analysis of the instantaneous power factor signal. Results obtained from experimental studies carried out under different speed and loads indicated that the detection of misalignment fault can be carried out successfully. The presented method can be used effectively without any additional cost since inverter fed motors have both voltage and current sensors. Also online monitoring of induction motors with the suggested method not only improves the motor's performance and longevity but also its efficiency. The main innovative parts of this study is that instantaneous power factor signal was used at the first time for detection of misalignment faults. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.