A phase voltage setting unit is configured to define an actual current phase region including a current phase error range based on parameters to which is added an individual difference of at least any one of a motor and an inverter. The phase voltage setting unit defines a stable operation current phase region in which a rotor position can be detected through sensorless control, and sets, as a target current, an electric current obtained by adding a phase difference corresponding to the number of revolutions detected by the revolution number detecting unit to an electric current set by current vector control, such that the actual current phase region is within the stable operation current phase region.