To provide a panel stopper set mechanism allowing a set head to be installed even if a set position of the panel stopper is deviated and allowing the panel stopper to be stably set and released.

When an axial center of a shaft 7a of a panel stopper 7 and an axial center of a set head 1 are deviated from each other and the shaft 7a of the panel stopper 7 is abutted on a tapered part 1a of the set head 1, the set head 1 resists against an energization power of parallel-plate springs 3a, 3b and moves in the direction to match the axial center with the axial center of the shaft 7a of panel stopper 7. When the axial center of the set head 1 coincide with the axial center of the shaft 7a of the panel stopper 7, a driving pin 8 of the panel stopper 7 is engaged with an engagement part 1b of the set head 1. A flexible shaft bearing 4 transmits rotation drive of an actuator 6 to the set head 1 even if the axial centers of the actuator 6 and the set head 1 are decentered.