Abstract: A conveyor system equipped with a roller track for holding and moving one side of material and a plurality of rails parallel to the roller track each having a carrier for holding and moving the other side of material on the rail, wherein each carrier is provided with a height adjuster for changing holding height of material, the holding height of material is raised after a carrier departs from the start point and the height adjuster engages with an operating bar which is set at a side of the rail, the holding height of material is lowered after a carrier departs from the end point toward the start point and the height adjuster engages with another operating bar which is set at a side of the rail, and the carrier which returns to the start point can pass below the material which moves while held at the carrier.