PURPOSE: To improve the feel of a material, the appearance and the durability by integratedly covering an auxiliary band which is different in at least the material or the color and consists of at least one kind of cement or clay on a decorative surface of an incombustible building material of incombustible composition.

CONSTITUTION: An incombustible building material is formed by extruding incombustible components such as cement and clay. An auxiliary band 4 which is different in at least the material or the color and consists of at least one kind of cement and clay is integratedly covered on at least a decorative surface 2 of the building material. The feel of a material, the appearance, the durability, the mechanical strength, the freezing and melting resistance, and the productivity are improved, and the cost is reduced thereby.