PURPOSE: To prevent adhesion of a fine particle in exhaust gas to the inside of a pipe and increase an EGR effect, by flowing the atmospheric air and pressure air in a back pressure pipe for negative pressure of opening an EGR valve not higher than a prescribed value.

CONSTITUTION: Intake and exhaust lines of an engine are communicated by a recirculating passage 27 provided with a back pressure type EGR valve 1, and exhaust gas is partially recirculated to the intake line. To a diaphragm chamber 8 in the EGR valve 1 negative pressure in an intake pipe is transmitted through a negative pressure port 20, further its negative pressure quantity is adjusted by a temperature sensing valve 3 and EGR vacuum modulator 2. A pressure chamber 16 in the modulator 2 is communicated with a fixed pressure chamber 9 and acted with exhaust pressure. While a back pressure pipe 10 is partially communicated to the atmospheric air through a check valve 4 further to an air pump 23 through an air selector valve 6, then the atmospheric air and pressure air are introduced into the pipe 10 in accordance with pressure in the diaphragm chamber 8.