A permanent magnet synchronous motor controller includes an inverter for supplying an alternating current power converted from a direct current power to a three-phase permanent magnet synchronous motor, having a pair of switching elements for each of said three phases of the motor; a smoothing capacitor for smoothing the direct current power connected to the inverter in parallel; and a control unit for controlling the motor by ON-OFF controlling each of the switching elements of the inverter, which further including a short circuit transition processing portion for changing control to 3-phase short circuit after performing precursory ON-OFF control of each of the switching elements so as to avoid occurrence of over current at an initial period of performing the 3-phase short circuit while the motor is being rotated.