PURPOSE: To cause a base material to evenly and adequately impregnate with varnish of high density by such an arrangement wherein a base material for laminated board is brought to contact with the surface of a revolving roll which rotates with its lower part kept immersed in varnish in a varnish tank and it is moved.

CONSTITUTION: Since a revolving roll 3 (preferably a rubber roll) rotates with its lower part kept immersed in varnish in a varnish tank 2, a layer of varnish in the varnish tank 2 rotates being adhered to the surface of the revolving roll. The layer of varnish on the revolving roll 3 and a base material, for laminated board are jointly pressed to the side 4 of the revolving roll by a press roll 5 and the base material 1 is impregnated with varnish.

EFFECT: Since varnish of high density is used, the loss of solvent in the process of impregnation is reduced.