To remove offensive odor and wet air in a room by automatically controlling a ventilator, save energy without automatically turning on/off the ventilator by estimating that the wet air in the room is desirably ventilated in a sleep mode and enjoy a comfortable life by using an automatically controlling function familiar with a user and serving to save the energy.

When the power witch of the room is turned on, a room lamp is lighted and the ventilator of the room is also operated. When the power switch is turned off, the room lamp put out and the automatically controlled ventilator still operates for a prescribed time (for instance, 5 minutes) and then automatically stops. When the room is not used thereafter, the automatically controlled vantilator automatically periodically repeats its operation and stop at intervals of a prescribed time (for instance, repeat at intervals of 30 minutes) (for instance, operates only for short time such as 5 minutes). When the room is not used for a long time (for instance, 12 hours), an automatic controller enters the sleep mode to stop an automatic on/off repeating function.