A molding material 22 from an extruding machine 33 is fed by a molding material feed pump 34 to a molding material discharge pump 32, which discharges the molding material from a coating gun 31 to a peripheral edge portion 21a of a multilayer glass panel 21. The rate at which the molding material 22 is discharged from the coating gun 31 is adjusted by controlling the rotational speed of the molding material discharge pump 32 depending on the relative speed between the multilayer glass panel 21 and the coating gun 31. An amount of molding material 22, which is commensurate with the difference between the rates at which the molding material 22 is fed to and drawn into the molding material discharge pump 32, is circulated through a flexible circulation hose 39 to the extruding machine 33.