A cable tray assembly includes a wafer table placed on a precision drive stage of which motions along specified mutually perpendicular X- and Y-directions are independently controlled. A plurality of conduits such as electrical and/or optical cables and gas- and/or liquid-transporting tubes are attached to the wafer table at one end and are also attached to an end portion of a planar elongated member extending in the X-direction. This elongated member is made of an elastic material and has a naturally arcuate sectional shape in the Y-direction. The other end portion of this elongated member is wound around a shaft extended in the Y-direction. The rotary motion and the axial motion in the Y-direction of the shaft are controlled by the same signals which cause the drive stage to move in the X- and Y-directions by the same distances such that the drive stage and the wafer table will move in synchronism with each other, minimizing the effect of cable drag on the wafer table.