An internal combustion engine having a controller for controlling the propriety of the target throttle opening degree is confirmed with a reference throttle opening degree as a reference by a monitoring device. The target throttle opening degree is calculated based on a target intake air quantity and a measured value or an estimated value of a supercharging pressure by using an inverse model of an air model expressing a dynamic relation that is established among the supercharging pressure, a throttle opening degree and an intake air quantity, by a first arithmetic unit.