PURPOSE: To set a carrier width of a printed substrate rapidly by moving a movable board of a first stage to a desired position and thereby moving an adjacent movable board and each of other movable boards to a desired position following in a chain.

CONSTITUTION: A number showing a movement amount of a movable board 32-1 of a first stage is inputted to a control circuit 21-1 and the movable board 32-1 of a first stage is moved toward a desired position. Since a light screening piece 12-1 arranged in the movable board 32-1 of a first stage also moves, a sensor part 11-1 arranged in a movable board 32-2 of the next stage turns ON. A motor 23-2 is driven based on a control signal sent out by a control circuit 21-2 which receives a signal 19-1 from the sensor part 11-1. Then, the movable board 32-2 of the next stage follows movement of the movable board 32-1 of a first stage. Similarly, other movable boards 32-3, 32-4 also follow movement of adjacent movable boards 32-2, 32-3 of preceding stages, respectively in a chain.