When the artificial air aperture 30 is open in step S160 and the air of lower dew condensation state (air of lower humidity) is introduced into the casing 10 via the ventilation port 40, the dew condensation state in the casing 10 is considered to change, for example, as shown in FIG. 8. That is, in winter or in the rainy season, the dew condensation state in the casing 10 in a parked vehicle increases.

Then, when power is applied to the ventilation control system 1 or the electronic device 15, dehumidified air is introduced into the casing 10 via the ventilation port 40. As a result, the dew condensation state is immediately alleviated (see the solid line [A] in FIG. 8). It is revealed that, according to the configuration of this embodiment, the dew condensation state can be rapidly alleviated to or below the guarantee condensation state compared to the case in which the casing 10 is made of metal and does not have the configuration of this embodiment (see the solid line [C] in FIG. 8) or the case in which the casing 10 is made of resin and does not have the configuration of this embodiment (see the solid line [D] in FIG. 8).

Although the casing 10 of this embodiment is made of resin, the casing 10 may be made of metal. In that case, substantially the same effect can be obtained (see the dashed line [B] in FIG. 8).

When the above steps are completed, the opening and closing control process ends.