In a plasma processing apparatus, a heating element 50 provided in a susceptor 12 is electrically connected to a heater power supply 58 disposed at an outside of a chamber 10 via an internal conductor 51 provided through the susceptor 12, a power feed conductor 52 provided across a space SP, a filter unit 54 and an electric cable 56. A casing 110 of the filter unit 54 is vertically fastened, from a bottom of the chamber 10, to an opening 114 formed in a bottom wall (base) 10a of the chamber 10 to be adjacent to a cylindrical conductive cover 42 that surrounds a power feed rod 40. The casing 110 is physically or electrically coupled to the bottom wall 10a of the chamber 10.