An ECU for controlling an engine counts the continued period of stopping the engine in a low-temperature environment. The ECU sets the idle rotational speed at a first idle rotational speed when the stopped period is below a predetermined threshold value, and at a second idle rotational speed higher than the first idle rotational speed when the stopped period exceeds the reference value. Accordingly, resonance at the driving force transmission system during idle operation can be prevented even in the case where a mount employed for attaching the engine to the vehicle is hardened as a result of undergoing a low-temperature environment for a long period of time, and the resonant rotational speed of the driving force transmission system including the engine varies.