As a conventional opening/closing control device of this kind, one described e.g. in PTL 1 is known. This opening/closing control device detects a speed of a vehicle (vehicle speed) by a vehicle speed sensor and opens a grille shutter in a low or middle speed operating state in which the detected vehicle speed is smaller than a predetermined speed. On the other hand, in a high speed operating state in which the vehicle speed is not smaller than the predetermined speed, the control device closes the grille shutter, whereby the introduction of ambient air into an engine room is blocked to reduce the resistance of air acting on the vehicle in the high speed operating state to thereby improve fuel economy.