PURPOSE: To make it possible to carry out a ventilation without making the heat within the room to escape and to be used as the ventilation fan for cooking by disposing a heat storage apparatus on the upstream side or downstream side of a rotary vane and varying the air flow direction of the rotary vane at an arbitrary time interval.

CONSTITUTION: When a rotary vane 1 is actuated so that air flows from the inside of a left-hand room of a wall 7 to the outside of a right-hand room of the wall, warm air within the room passes through a heat storage apparatus 5 and is discharged out of the room. Upon this occasion, the heat storage apparatus 5 absorbs the heat of warm air within the room. Then, conversely at this time, when the rotary vane 1 is operated so that air flows from the outside of the room to the inside thereof, cool air outside the room is warmed by heat stored in the heat storage apparatus when it passes therethrough, and warm air flows into the room. As described above, when the air flow direction is changed by the operation of the rotary vane 1 at a predetermined interval, the ventilation within the room becomes possible without letting the heat within the room to escape out of the room. When soot generated at the time of cooking is discharged out of the room, the heat storage apparatus is contaminated by the soot, and the function of the heat storage apparatus is impeded. Hence, the heat storage apparatus is disposed at a position apart from the air duct.