To simplify a structure by suppporting a drive device on two support members for winding parts axially arranged parallel to each other, which are partly overlapped and positionally shifted and fitting the drive means to rotate two winding parts to the support member.

A first winding part 2 and a second winding part 3 having mutually parallel axes are axially arranged parallel to each other. The vicinal part of the right end of the winding part 2 and the vicinal part of the left end of the winding part 3 are partly overlapped in the axial direction and further, positionally shifted. A drive means composed of a motor 6 and a driving force-transmittion mechanisms 22, 23 to rotate the winding parts 2, 3 is attached to brackets 4, 5 of the both winding parts 2, 3. The brackets 4, 5 are originally provided to rotatably support the winding parts 2, 3 in a roof-space S. Hence, the drive means can be fitted while making use of members originally necessary for the winding parts 2, 3. Therefor, a drive device for a building shutter can be constituted of a simple structure.