PURPOSE: To prevent liquid material from scattering on a panel transferred in a fixed direction for the sake of safety and health, by discharhing the liquid material contrary to the moving direction and film-casting it on the panel.

CONSTITUTION: Liquid material such as heat insulating raw material, and the like is film-casted nearly in a uniform thickness on the building panel material 7 which is transferred in a fixed direction. In this case, the liquid substance is spread in a uniform thickness on the panel material, as it is discharged through a nozzle 1 in a film shape along an arcuate discharging locus B contrary to the moving direction of the panel material 7.