PURPOSE: To assist starting, by increasing suction heating by enlarging the quantity of EGR gas when starting, in a diesel engine.

CONSTITUTION: A throttle valve 7 is mounted to the stream side upper than an injection port 6 to a suction passage 2 of EGR gas. A controller 8 is installed which provides the throttle valve 7 with closing signals when starting an engine. Thus, a large quantity of EGR gases are injected into suction through an EGR passage 4 because an EGR valve 5 is opened an the throttle valve 7 is closed when starting. Consequently, starting capacity is imoroved because a large quantity of residual oxygen and combustible fuel in exhaust gas function as both suction heating action and the supply working of evaporated fuel.