To prevent a lock member from locking a panel again by quickly rotating the panel in the panel opening direction when the panel is unlocked.

When a panel 30 is unlocked from a lock member 35, it rotates by the force of a biasing member in a direction α1 such that a noncoupling hole 32c of the panel 30 slides a pin 41b to quickly rotate up to an angle θ, without receiving the resistance of a damper 43, then the edge of the hole 32c is coupled with the pin 41b to rotate a sector gear 41, together with the panel, causing the damper 43 to be driven to slowly rotate the panel. Since the panel 30 initially quickly rotates when being unlocked, the panel is never locked again by the lock member 35.