PURPOSE: To improve the engine brake effect by operating a motor-driven dynamo as dynamo according to the signal of an engine brake operation-state detecting means, in the turbocharger equipped with a motor-driven dynamo installed onto the shaft.

CONSTITUTION: A motor-driven dynamo MG is installed at the center part of the shaft 7 of a turbocharger 1 consisting of a compressor 8 and a turbine 9. A controller 23 judges that exhaust brake is necessary when the engine load is less than a prescribed value, and the speed change stage is at the speed change position suitable for the operation of an exhaust brake and a clutch pedal is in no-stepped state. With this judgement, MG is operated as dynamo in order to apply a load onto the exhaust brake, and the output current is detected by a current detector 31. The output electric current of the dynamo is used for the charge of a battery 32, and the electric power is supplied into the MG which is used as electric motor in the case when the output is increased with the engine at low speed.