A plasma processing apparatus is provided to insulate completely a chamber and a valve housing by having a bolt made of an insulator such that the bolt couples the chamber to the valve housing while including a washer and a tube made of an insulation material in a contact portion of the bolt and the chamber. A plasma processing apparatus(100) is composed of a plurality of chambers and a gate valve(140) installed between the chambers wherein the gate valve controls a transfer of a substrate and opening of each chamber. The gate valve is coupled by an insulation bolt so that the gate valve is insulated from the chambers and RF power is not induced. The chamber can be a process chamber(130) or a transfer chamber(120).
