PURPOSE: To reduce the power load on a battery by joining an electric turning equipment which is a motor generator, with the output shaft of an engine and mounting a braking mechanism which brakes the engine via a clutch mechanism, on the turning shaft of this electric turning equipment.

CONSTITUTION: A primary electric turning equipment 3 is mounted on a turning shaft 12 which is directly connected to the compressor 13 of the turbine 11 of a turbo-charger 1 so that a stator 32 generates AC power when the rotor 31 of said equipment 3 is driven. When the specified AC power is fed across the stator 32, the turning equipment 3 functions as a motor to turn and drive the compressor 13. A secondary electric turning equipment which is also a motor generator is mounted on the output shaft of an engine 2 via a gear mechanism 41 and a braking mechanism 5 in which when the compressor 52 is driven at high speed, air is compressed to apply the braking force to the engine 2 is joined with the shaft 42 of the rotor via both a clutch 6 and an accelerating ger mechanism 53.