PURPOSE: To prevent the infiltration of the outside air into a car and prevent the occurrence of a quick temperature change in the car by temporarily stopping a louver at the maximum swing angle guiding the blowout air to the door open side of a car body when a door is opened, and continuously blowing the blowout air to the door open side.

CONSTITUTION: When doors 8... on one side section 14a are opened and a door opening/closing signal is inputted and a louver 5 reaches the maximum swing angle with its tip section faced to one side section 14a, for example, a geared- motor 16 is turned off to stop the louver 5, and the guide direction of the blowout air 10 by the louver 5 is fixed on one side section 14a, i.e., door open side. An air curtain is formed at an opened entrance 6 to block the entrance 6, and the inflow or outflow of air through the entrance 6 is prevented. The introduction of the outside air is prevented by a ceiling fan device 5a, the inflow quantity of the outside air through the entrance 6 is sharply reduced, and a quick temperature change in a car 4 is prevented.