A control apparatus for a switching circuit includes a controller, a target-rotational-speed acquiring device, a target-torque acquiring device, and an ON-time varying device. The controller is configured to turn on a bidirectional conduction switching device provided parallel to a reverse conducting device through which a commutation current flows. The target-rotational-speed acquiring device is configured to acquire a target rotational speed of an alternating current motor. The target-torque acquiring device is configured to acquire a target torque of the alternating current motor. The ON-time varying device is configured to vary, on a basis of the target rotational speed and the target torque, an ON time period during which the bidirectional conduction switching device provided parallel to the reverse conducting device through which a commutation current flows is turned on.