Engine control apparatus and method

By using a model of a transient response characteristic of an engine and a model of a steady-state characteristic of the engine, a disturbance estimate value is calculated. By using this disturbance estimate value, initial command values of a nozzle opening degree of a Variable Nozzle Turbo and a valve opening degree of a Exhaust Gas Recirculator are adjusted in order to reduce model errors and appropriately handle the disturbance. Hence, it is possible to cause Mass Air Flow and Manifold Air Pressure to follow their target values stably.