DLC (Diamond-Like Carbon), a kind of the hard carbon film, has such features as the lowest friction coefficient among various ceramic coating materials, high hardness, and less damage in the counterparts. Because of these features, many developments regarding the application for various kinds of sliding parts are in progress. However, people now call other films DLC, too, even though they are different from those defined in ‘80 s. Moreover, new manufacturing methods such as sputtering and cathodic arc ion-plating are now used in addition to the conventional ones such as the radio frequency (rf) plasma assisted chemical vapor deposition (PACVD) and the ion beam deposition. It is required to use these DLCs properly for each usage. Another topic in these days is a flexible DLC film that uses rubber as the substrate material instead of the generally used ones such as metals and ceramics. This new DLC film is applied to the rubber seal ring (O-ring) for zoom lens system of 35 mm compact cameras.