PURPOSE: To provide press boards for electric insulation having a low relative dielectric constant and moreover excellent electric and mechanic characteristics.

CONSTITUTION: Resin, composed of ethylene-methacrylic acid copolymer, is added to a substance, in which kraft pulp is disaggregated to form a fiber state, is mixed then combed to be laminated in a wet paper condition, and is dry-integrated by heat-compression to form electric insulation press boards. The carboxyl group of the ethylene-methacrylic acid copolymer is reaction-joined with the hydroxyl group of the kraft pulp, consequently press boards for electric insulation can be provided, in which a relative dielectric constant is sharply lowered and water resistance and an insulation characteristic, etc., are improved.