Abstract: A lock lever bracket fixed to an upper rail and serving as a lock mechanism for locking the upper rail sliding relative to a lower rail includes shaft support holes which are separated from each other in the slide direction of the upper rail and through which an open rod is inserted. A lock lever includes two bearing portions which are disposed close to both shaft support holes of the lock lever bracket and a rotation transmission groove. The open rod includes a linear shaft portion which extends through each shaft support hole and each bearing portion and a bent portion which engages with the rotation transmission groove of the lock lever and rotates along with the linear shaft portion so as to rotate the lock lever in the unlock direction.