PURPOSE: To prevent production of scratch and to prevent the generation of friction noise, by a method wherein a slide blade having a sloped support table surface is slidably mounted in the body frame of a track.

CONSTITUTION: Only when a product 1 is conveyed in an advancing direction, a carriage 9 is raised, the product 1 is floated up from a skid rail 3, and the product 1 is conveyed without sliding. During backward movement, the carriage 9 is lowered, and the product 1 is moved backward in an arbitrary position. The raising and the lowering stroke of the carriage 9 are freely changed according to a span size (l) of each of a stopper, mounted to a slide plate 8 and a stopper, mounted to a body frame 7b, and an inclination angle θ of an sloped support table surface 8a.