An ECU for controlling an engine counts an unused time TIM of engine in a low-temperature environment. If the unused time TIM is shorter than a predetermined reference value, the ECU sets idle speed immediately after start of operation of the engine to a first idle speed, and if the unused time TIM is longer than the reference value, sets the idle speed to a second idle speed higher than the first idle speed. If duration of the second idle speed exceeds a reference period determined by state of driving of the vehicle, the ECU sets the idle speed to be lower than the second idle speed. In this manner, increased vibration in idling operation in a low-temperature environment can be prevented.