A ventilation device includes a temperature regulating coil that is capable of changing the cooling capacity at multiple stages, and that cools a supplied-air flow after having undergone total heat exchange by a total heat exchanger, a target indoor-humidity storage unit that stores therein a target indoor humidity that is a target value of the indoor-air humidity, and a control unit that decides the cooling capacity of the temperature regulating coil, such that the humidity of the supplied-air flow becomes the target indoor humidity, based on measurement values of an outside-air temperature sensor and an outside-air humidity sensor when the target indoor humidity is lower than an actual measurement value of the indoor-air humidity measured by an indoor humidity sensor.