To properly correct the output of an oxygen sensor in response to the pressure dependency of each oxygen sensor and guarantee the accurate control of an engine corresponding to the output of the oxygen sensor by correcting the output of the oxygen sensor based on the counter-pressure change rate of the oxygen sensor.

An oxygen sensor 10 detecting the oxygen concentration of the intake air is arranged downstream the EGR gas guide port 8 of an intake pipe 4, an intake pressure sensor 11 is arranged near the oxygen sensor 10, and their signals are sent to an ECU20. The ECU20 drives a solenoid valve 15 based on the input signals and controls the feed of the negative pressure stored by a vacuum pump 16 into the diaphragm chamber of an EGR valve 9. The ECU20 calculates the counter-pressure change rate of the oxygen sensor 10 based on the output of the oxygen sensor 10 and the output of the intake pressure sensor 11, corrects the output of the oxygen sensor 10 based on the calculated counter-pressure change rate, and uses the corrected output of the oxygen sensor 10 for the opening control of the EGR valve 9.