A multi-layer structure comprising a functional resin layer obtained by covering a core layer of a base body resin or a second functional resin with a shell layer of a first functional resin, and a base body resin layer containing the functional resin layer therein. The layers of the functional resins are formed at positions where they are allowed to exhibit their functions to a sufficient degree, a plurality of functions can be imparted, and a molten resin mass having the above multi-layer structure can be formed by the compression-forming.