NOVELTY - The plasma processing apparatus has a circular chamber (30) with an opening portion that serves as a plasma ejection port (8) surrounded by a dielectric member, a gas supply pipe (10) that introduces gas into the inside (7) of the chamber, a coil (3) provided at the vicinity of the chamber, and a base material mounting table. A high-frequency power supply is connected to the coil.    USE - Plasma processing apparatus for thin film on a base material, e.g. for crystallization of thin film transistor (TFT) semiconductor film or modification of solar cell semiconductor film. Uses include but are not limited to thermal treatment, thermal spraying, film formation, and etching. Can also be used in cleaning or degassing reduction of protective layer in plasma display panel, surface flattening or degassing reduction of dielectric layer constituted by collection of silica fine particles, reflow of variety of electric devices, and plasma doping using solid impurity source.    ADVANTAGE - Ensures excellent stability of thermal plasma (small variation over time) and little contamination of electrode materials into the base materials due to electrodeless discharge. Allows stable and efficient generation of plasma and ensures efficient treatment of all the desired regions to be treated of base material within short period of time since induction coupling plasma is generated using small high-frequency power by making the distance from solenoid coil to chamber the same at arbitrary portion of solenoid coil. Prevents leakage noise of high frequencies and abnormal discharge by surrounding the induction coupling-type plasma torch unit by wholly grounded shielding member made of conductor. Performs treatment of large-scale substrate or the like within short period of time without increasing the size of plasma processing apparatus since induction coupling-type plasma torch unit or base material mounting table is preferably moved in horizontal direction and in perpendicular direction to the paper surface. Improves plasma generation efficiency since high-frequency electric power exerting per unit volume increases due to the volume of chamber becoming small. Obtains plasma ejection with larger intensity by shortening the path for suppressing the intrusion of circular plasma. The service life of products is extended by effectively suppressing the concentration of deterioration of respective quartz blocks at specific portions. The phenomenon in which plasma flow ejected from both end portions of plasma ejection port becomes excessive is suppressed using a simple configuration in which a path communicating the chamber and opening portion is provided in parallel with the longitudinal direction of opening portion. Allows irradiating the base material with high-temperature plasma and decreases the torch unit to extreme extent since planar spiral coil is provided above the inside dielectric block instead of the solenoid coil. The plasma generation efficiency is improved by providing uniform plasma and minimizing the volume of portions in which plasma is generated.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a plasma processing method.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross sectional view of the plasma processing apparatus.    Coil (3)    Inside (7)    Plasma ejection port (8)    Gas supply pipe (10)    Chamber (30)