PURPOSE: To make it possible to generate a boost pressure which is adaptable to a rapid acceleration so as to enhance the accelerating performance by controlling a motor-generator (rotary electric machine) fitted on the rotary shaft of a turbocharger in accordance with the rotation speed of the engine and the depressing amount of an accelerator pedal.

CONSTITUTION: A rotary electric machine 3 is fitted on the rotary shaft 2c of a turbocharger 2 having an exhaust turbine 2b and a compressor 2a. When the rotary electric machine 3 is driven so as to serve as a generator, a.c. power produced from the rotary electric machine 3 is fed through a power converter 4 and is charged into a battery 5. When the electric machine 3 is driven so as to serve as a motor, control is made such that the power from the battery 5 is fed to the rotary machine 3 through the power converter 4. In this phase a required boost pressure is calculated from the rotational speed of the engine and the depressing amount of an accelerator pedal, and when rapid acceleration of the engine is determined in accordance with the deviation between the required boost pressure and an actual boost pressure, the rotary electric machine 3 is driven so as to serve as the motor to raise the boost pressure.