To integrate a charging circuit with the control element and peripheral circuits of a driving or hydraulic motor operator circuit, by using the chopper control element of the operating circuit in a normal mode for controlling the charging of a battery in a charging mode by means of a chopper.

A plugging diode 16 which acts as a flywheel to continuously feed an armature current is connected in parallel with a serial circuit of an armature 15 and a field coil (choke coil) 9. A battery motor current (IBM) is detected by means of a current sensor 17. In a state where the b- and c- contacts of a contractor CN1 are connected, a charging circuit is formed and, in another state where the a- and c-contacts of the contactor CN1 are connected, a motor operating circuit using a battery 10 as a power source is formed. The speed of a motor can be controlled by means of a chopper control element CH5 in a chopper at a prescribed duty ratio.