a diaphragm 32 extending across the interior of the valve housing 30 to provide an exhaust gas chamber 34 and a vacuum chamber 36 the vacuum chamber 36 is connected through a vacuum level control valve 38 to the second port 40 of the intake passage 12 provided downstream of the throttle valve 18 the vacuum level control valve 38 is responsive to a control signal from an electronic control circuit 90 for introducing a controlled degree of vacuum from the suction vacuum developed in passage 12 into the egr valve vacuum chamber 36 to control the opening of the egr valve 28 so that egr flow can be controlled in accordance with intake air flow or engine suction vacuum appearing in the intake passage 12 downstream of the throttle valve 18 an orifice 42 is provided in the egr passage 24 downstream of the egr valve 28 i e between the egr valve 28 and the first port 26 in order to detect suction vacuum appearing in the intake passage 12 downstream of the throttle valve 18 a suction vacuum sensor 44 is provided which comprises a sensor housing 46 a partition 48 formed centrally with a through hole 50 and extending across the interior of the sensor housing 46 to form first and second pressure chambers 52 and 54 and a semiconductor pressure sensitive element 56 which may be taken in the form of a si strain gauge mounted on the partition 48 within the second pressure chamber 54 to close the through hole 50 the first pressure chamber 52 is connected through a vacuum introduction tube 58 to the third port 60 of the intake passage provided downstream of the throttle valve 18 and the second pressure chamber 54 is evacuated so that the pressure.