To improve start accelerating performance when starting from an engine stop condition by an idling stop control, in an automobile for performing the idling stop control and equipped with a turbocharger with an electric motor.

When an engine 1 is stopped by the idling stop control and the shift lever of an automatic transmission is retained within a traveling range, the electric motor 11b built into a turbo unit 11 is started and the turbo unit 11 is forcibly driven by the electric motor 11b. From this condition, if an internal combustion engine starting condition is set up and the start operation of the engine 1 is started, the turbo unit 11 is already driven and rotational inertial force is produced in a turbine compressor 11a. Thereby, rise of a supercharger rotational speed at a point of starting the automobile is expedited, favorable supercharging is performed, and excellent start accelerating performance is provided.