A delay time is provided in a calculation process until an instructed throttle opening is outputted after a required cylinder inside air filling efficiency is inputted. When calculation timing of a fuel injection quantity comes, an actual cylinder inside air filling efficiency which is achieved in a time ahead by the delay time from the present time is estimated by using an air response model. When a read-ahead time from the present time to closing timing of an intake valve exceeds the delay time, a change amount of the actual cylinder inside air filling efficiency which occurs by the time the read-ahead time elapses from a time point when the delay time elapses is estimated by using an air response model with a deviation between an estimated actual cylinder inside air filling efficiency after the delay time and a target cylinder inside air filling efficiency as a step input value.