This article proposes a self-sensing control method considering a position sensor fault detection and algorithm transition, which can be applied to a self-sensing control based on back-electromotive force estimation for an interior permanent magnet synchronous motor (IPMSM). An adaptive threshold method is derived to accomplish not only the stable transition between the sensored control and the self-sensing control but also the fast fault detection. Although an appropriate threshold value is selected by considering the maximum overshoot of the difference between measured value and estimated value, the adaptive threshold method is needed for the fast fault detection because the maximum overshoot exceeds the selected threshold value during acceleration and deceleration. Therefore, the improved adaptive threshold method is proposed for the high reliability of IPMSM control system. The feasibility of proposed method is assessed in simulation and experimental results.