Regarding the function of the silicone release agent, the following two mechanisms, that is, the low energy surface of a cross-linked methyl hydrogen polysiloxane (MHPS) resin and the separation of a non-cross-linkable dimethyl polysiloxane (DMPS) oil itself have been compared. The 180 degrees peel strength of the glass plate/silicone release agent/pressure sensitive adhesive (PSA) tape laminates decreased in the following order: un-coated>MHPS-coated>DMPS-coated glasses. ATR, ESCA and SEM observations of the PSA and glass surfaces after the peel test showed that no MHPS transferred from the glass surface to the PSA but a part of the DMPS transferred. From these results, it was concluded that, for decreasing peel strength, the separation of silicone oil (DMPS) itself is more effective than the low energy surface of the silicone resin (cross-linked MHPS).