An internal combustion engine includes parallel first and second intake passages, and the intake passages respectively include first and second superchargers. A first airflow meter measures the intake air amount in the first intake passage. A second airflow meter measures the intake air amount in the second intake passage. An ECU obtains an air amount difference between the intake air amount measured by the first airflow meter and the intake air amount measured by the second airflow meter to compare the obtained air amount difference with a predetermined abnormality determination value. The ECU determines that an abnormality has occurred in one of the superchargers when the air amount difference exceeds the abnormality determination value. The abnormality determination of the superchargers is based on the air amount difference between the intake passages. This accurately determines the occurrence of an abnormality in the superchargers regardless of structure of the intake passages.