In a step S64, a value Cqe corresponding to an EGR flow speed is calculated by using the shown equation (Cqe={K(Pexh???Pm)}??? in which K is a constant) and in a step S65, an opening area of the EGR valve Aev is calculated from the shown equation (Aev=Tqek/Cqe) by using a required EGR amount Tqek and the EGR flow speed corresponding value Cqe.