PURPOSE: To improve working efficiency by forming an interior decoration base material by way of impregnating a felt layer with a synthetic resin solution mixed with a colorant and forming a surface layer of a synthetic resin coating layer containing a colorant which is the same in color as the colorant with which the felt layer is impregnated.

CONSTITUTION: A felt layer 15 of desired thickness is continuously formed with a needle punch 23 by way of adding a synthetic resin fiber to worsted of a rag opening felt or others and mixing an acrylic resin binder with it. This layer 15 is sequentially inserted in a tank 25 containing an acrylic resin solution 17. And an interior decoration material 12 is formed by drying the felt layer 15 by a heat drying means 29. The acrylic resin solution 17 in the tank 25 is mixed a colorant 19. Thereafter, an excessive amount of the acrylic resin solution 17 is squeezed out between a pair of rollers 27. Subsequently, a synthetic resin coating 21 is applied on the surface of a base material 12 with a spray. This coating 21 contains a colorant made of a black pigment which is the same in color as the colorant 19 with which the layer 15 is impregnated. A surface layer 13 is formed by hardening of the coating 21.