PURPOSE: To obtain an air flow direction changing device which is inexpensive in cost and performs a positive operation as it satisfies conditions necessary for the operation by automatically carrying out change of air flow by means of a drive motor and a speed reduction mechanism and stopping the device at its upper limit position or its lower limit position.

CONSTITUTION: In a case where a manual switch 21 is closed, when a such up temperature is lower than a set value, a movable contact (c) of a thermostat 20 comes into contact with a movable contact (b) thereof, and power is supplied to a motor 1 through a upper limit position detecting microswitch 18. Accordingly, when a damper 14 is not in the upper limit position (a cool air blow-off position), the damper 14 makes an arcuate motion around a stationary shaft 16 through a gear box 12 and the like and reaches the upper limit position, thus opening the contact of the microswitch 18 and stopping. When the blow-off temperature rises higher than the set temperature from this state, the movable contact (c) of the thermostat 20 comes into contact with the stationary contact (a), and power is supplied to the motor 1 through a lower limit detecting microswitch 17, and the damper 14 reaches the lower limit position (hot air blow-off position) and comes to a stop.