PURPOSE: To reinforce a real Japanese paper by performing surface and inner protective treatments of the paper and to apply it to a construction material such as a floor material and a wall material.

CONSTITUTION: A base 1 of a construction material is adhered with a swollen and softened Japanese paper 3 and inner protection of the Japanese paper 3 is performed by sealing wall holes 3a of fibers of the Japanese paper 3 and then, the surface is treated with a water repellent coating 4 to provide water resistance, wear resistance etc. It is possible thereby to make a good use of an image of the Japanese paper with simplicity and warmth and to provide a construction material being washable with water and durable.