Abstract: An apparatus for driving an automatic door to reciprocate includes an elongated horizontal mounting member, and a sliding block disposed slidably on the mounting member. A left cable has a first end fastened to one of a left end of the mounting member and a left side of the block, and a second end fastened to a left side of the door. A right cable has a first end fastened to one of a right end of the mounting member and a right side of the block, and a second end fastened to a right side of the door. Each of the left and right cables has an intermediate portion, which is guided to extend along a snakelike path and which includes a plurality of parallel horizontal cable portions that are arranged one above another and that extend in a longitudinal direction of the mounting member. As such, the distance traveled by the door can be several times that of the sliding block.