A reversing unit includes a fixed plate, a first movable plate provided so as to face one surface of the fixed plate, a second movable plate provided so as to face the other surface of the fixed plate and a rotary actuator. The rotary actuator rotates the first movable plate, the second movable plate and the fixed plate around a horizontal axis. A distance between the first movable plate and the fixed plate and a distance between the second movable plate and the fixed plate are set to be substantially equal to a difference in height between two hands of a main robot that carry a substrate in and out.