A permanent-magnet synchronous motor includes an inverter power circuit that converts direct-current power to three-phase alternating-current power, a motor bodydriven by the three-phase alternating-current power, a current detector that calculates an excitation current value and a torque current value from motor stator current values and an estimated value of a magnetic pole position of the rotor, a magnetic pole position detector that determines, for output to the current detector, the estimated value from the excitation current value, the torque current value, and supply voltage information, a voltage calculation unit that calculates, by means of the excitation current value, the torque current value, and an angular velocity calculated from the estimated value, the supply voltage information that causes the torque current value to approximate a torque current command value, and an inverter controller that controls the inverter power circuit on a basis of the supply voltage information and the estimated value.