An intake air quantity correcting device calculates an intake air quantity as a sensing target of an airflow meter (an intake air quantity sensor) based on an injection quantity sensing value sensed with a fuel pressure sensor (an injection quantity sensor) and an oxygen concentration sensing value sensed with an A/F sensor (an oxygen concentration sensor). The intake air quantity correcting device regards a difference between the intake air quantity calculation value calculated in this way and an intake air quantity sensing value sensed with the airflow meter as a sensing error of the airflow meter and corrects the intake air quantity sensing value of the airflow meter based on the sensing error.