A motor controller is provided which can be reduced in the number of the wirings and power semiconductor devices required while maintaining the function equivalent to or higher than that of the motor controller adopting the existing winding changeover scheme, thereby realizing cost and size reduction and life increase. The motor is made in a structure having motor windings opened at both ends. The one end terminals of phase windings are respectively connected to the output terminals of a first inverter circuit while the other end terminals are respectively connected to the output terminals of a second inverter circuit. During power generation, any one of the inverter circuits is driven on all the phases by means of a same control pulse.