PURPOSE: To prevent an oversupercharging by setting a reference steam set pressure at higher value as the operating range of higher set pressure of a supercharging pressure control means in the body performing the restraint control of an engine output separately from the control of a supercharging pressure in case of the supercharging pressure becoming more than a reference set pressure.

CONSTITUTION: The engine A provided with an intake air supercharger B is equipped with a supercharging pressure control means D controlling the supercharging pressure detected by a supercharging pressure detection means C in a set pressure according to the engine running state. It is also provided with the engine output control means E restraining the engine output separately from the supercharging pressure control in case of the supercharging pressure becoming more than a reference set pressure with the specified set pressure (reference set pressure) higher than the said set pressure corresponding to the engine running state related to the supercharging pressure control means D as the reference. In this case, the reference set pressure of the engine output control means D is made to set at higher value as the running range of higher set pressure of the supercharging pressure control means C.