The rotational acceleration of an engine is calculated based on a detection value of an engine rotating speed, the inertia torque to be transmitted to a variable valve mechanism, such as a variable valve timing control mechanism or the like, is calculated based on the rotational acceleration, a correction amount of a manipulated variable for the variable valve mechanism, which is in compliance with the inertia torque, is calculated, and the manipulated variable for the variable valve mechanism is corrected with the correction amount according to the inertia torque, to thereby control the variable valve mechanism based on the corrected manipulated variable.