The mechanism by which surface modification of two kinds of synthetic rubbers (ethylene-propylene and chloroprene) was brought about by ultraviolet (UV) irradiation and sputter ion etching treatments was studied from a physicochemical point of view. The most remarkable effect of this irradiation treatment was the rapid increase in adhesion properties and the simultaneous decrease in self-stickiness. This nonsticking effect was particularly important for the rapid production of articles from thin rubber sheets. The surface modification mechanism was studied by use of SEM, ESCA, FTIR, and related interfacial analytical procedures. It was shown that surface roughening with a quite thin layer of surface oxidation (similar to 0.5 mu m in depth) is a key factor for the development of nonsticking properties.