A device for adjusting the seat depth of a motor vehicle seat includes a base element to be arranged in a manner fixed on the seat framework, a supporting element which is mounted in a longitudinally movable manner on the base element and is intended for supporting a seat user and guide device by means of which the supporting element is guided movably on the base element along an adjustment direction. The guide device includes a first guide mechanism, in the vicinity of which the supporting element is supported on the base element and at which the supporting element and the base element interact with play in a direction perpendicular to the adjustment direction and to the supporting direction, and a second guide mechanism with which the supporting element is guided on the base element in an essentially play-free manner perpendicular to the adjustment direction and to the supporting direction.