To remove only silver paste 63 entered round into the undersurface of a screen 20 and to leave the silver paste in an opening 62 of the screen 20 as it is in a screen printing apparatus in which the silver paste 63 is applied on a specified position of a circuit substrate 65.

While a cleaning fabric 44 fed by a feeding roll 45 and wound by a winding roll 46 is press-contacted to the undersurface of the screen 20 by a pressing member 49 which is not rotated, the whole cleaning unit 38 is moved in the lengthwise direction of the screen 20. Then, after wiping with the cleaning fabric 44 is finished, air is jetted to the undersurface of the screen 20 by a flat air nozzle 56 to blow off fibers generated with the cleaning fabric 44 and to suck and eliminate them by a suction nozzle 60.