A large number of small reflection portions are continuously formed over a back face of a base member opposite the light impinging side, in an arbitrary arrangement. The small reflection portions are each formed to have a boundary surface for reflection, interference, and diffraction of incident light impinging onto the base member, to thereby produce random changes in the brightness of reflection light over the entirety of the decoration panel. A reflection layer is formed on the boundary surfaces of the small reflection portions such that the boundary surfaces function as mirror surfaces and reflect light propagating through the base member toward the front face of the base member.