To lessen the number of switches for supplying DC voltage to two or more DC motors by building an apparent H bridge with a switch pair constituted of a first and a second switch and other switch pairs, each of which is constituted of a switch at the high potential side and a switch at the low potential side.

Serially connected pairs of a first switch 5 and a second switch 6, a switch 7 and a switch 8, and a switch 9 and a switch 10 are connected to the output of a rectifier 2 through a reactor 3. At that time, the switches 5, 7, 9 are connected to the high potential side of a DC power supply and the switches 6, 8, 10 are connected to the low potential side of the DC power supply. By using a complementary PWM driving signal which reverses the on/off control between the switches which make a pair as for a control signal (driving signal) for controlling the pairs of switches 5 and 6, 7 and 8, and 9 and 10, the magnitudes and polarities of the voltages V1, V2 to be applied to motors 11, 12 respectively can be separately controlled.