PURPOSE: To improve running performance of an engine while reducing NOX by closing in a medium load region an auxiliary valve provided on the way of a vacuum piping for transmitting controlling, negative pressure from an EGR port to a negative pressure responsive system EGR valve.

CONSTITUTION: The heading device circulates a portion of exhaust gas from an exhaust system through an EGR valve 1 to an intake system, and the EGR valve 1 is controlled by controlling negative pressure transmitted from a carbureter EGR port 3 through a vacuum piping 4 to a negative pressure operated chamber 11. A negative pressure modulator 5 is interposed in the vacuum piping 4 to adjust said controlling negative pressure to a proper value. In this case, an auxiliary valve 20 is interposed on the way of the vacuum piping 4 betwee the EGR port 3 and the negative pressure modulator 5 and has a first valve body 22 for closing a first path 24 in a valve casing 21 and a second valve body 26 for closing a second path 25 in the same valve body 22 to functionally close the piping 4 in the medium load region.