An internal combustion engine is equipped with a downstream temperature sensor arranged in an intake passage, an upstream temperature sensor arranged in the intake passage upstream of the downstream temperature sensor, an EGR temperature sensor arranged in an EGR passage, and an airflow meter arranged in the intake passage. A control device corrects a temperature detected by each of the temperature sensors based on an amount of deviation of the temperature detected by that one of the temperature sensors upon activation of the control device after the lapse of a prescribed time or more since stoppage of the internal combustion engine from a reference temperature. Then, the control device calculates a flow rate of EGR gas based on the corrected temperature of that one of the temperature sensors and a flow rate of intake air, and detects the clogging of the EGR passage based on the flow rate.