A sliding device includes a fixed rail, a movable rail, a lock plate, a spring member, and a first stopper and a second stopper provided on the lock plate. The lock plate is held by the movable rail, and is displaceable between a locking position where the lock plate engages with the fixed rail and a non-locking position where the engagement is released. The spring member can exert an elastic force to maintain the lock plate in the locking position. The first stopper locks and fixes a first end of the lock plate to the spring member. The second stopper locks and fixes a second end of the lock plate to the spring member.