A guide pin is set in common in first and second voids defined in the peripheries of first and second flexible printed wiring boards. The second void has the shape identical to the shape of the first void. When the guide pin rotates around a rotation axis so as to bring the guide pin in contact with the peripheries of the first and second flexible printed wiring boards inside the first and second voids, the first and second flexible printed wiring boards can be arranged. This leads to arrangement of the first and second flexible printed wiring boards at a time in a facilitated manner.