PURPOSE: To reduce an assembling man-hour and to facilitate maintenance by providing a drive motor for switching a damper under a body.

CONSTITUTION: Openings 3 communicating with connecting adapters 1 are provided in a body 2 of a VAV apparatus having the adapters 1 at front and rear sides, a groove 4 is formed adjacent in one direction of the opening 3, and a heat insulator 5 formed of foamed styrene, etc., to be vertically divided to upper and lower parts is provided. A cylinder 8 to be opened or closed by a rotation of a shaft 7 is provided at a center in a circular damper 6. Further, a bearing container 10 for containing a bearing 9 of the shaft 7 is provided at an upper part, a support base 12 for supporting a drive motor 11 for driving the shaft 7 is provided at a lower part to form a damper holder 13. The holder 13 is engaged with the groove 4 of the insulator 5, the motor 11 is detachably mounted with screws 14 at the base 12 formed at a lower part of the holder 13 in a state exposed from the body 2, and connected to the shaft 7 via a connector 5.