A limit range setting section sets a primary limit range from a primary lower limit phase to a primary upper limit phase within an interval from a minimum torque phase to a maximum torque phase in a voltage phase-torque map. The limit range setting section calculates a phase obtained by adding a maximum amount of offset error of a rotation angle sensor to a zero phase as a secondary upper limit phase, and calculates a phase obtained by subtracting the maximum amount of offset error from the zero phase as a secondary lower limit phase. The limit range setting section sets a range from the primary lower limit phase to the secondary upper limit phase when a command torque is negative, and a range from the secondary lower limit phase to the primary upper limit phase when the command torque is positive as a secondary limit range.