PURPOSE: To detect the failure of an EGR control valve that the EGR control valve is kept open.

CONSTITUTION: A temperature sensor 52 is arranged in an EGR (recirculated exhaust gas) passage 12. A counter is provided in which a counted value is increased or decreased following a temperature in the EGR passage 12 during normal operation of the EGR control valve 14. Judgement is made that the EGR control valve is kept open when, in transition from an operating condition to supply EGR gas to an operating condition to stop the supply of the EGR gas, a difference between a temperature in the EGR passage before the transition and a temperature in the EGR passage at a lower-limit counted value after transition is below a certain value.