A plasma processing method capable of processing an object with fine linear portions. The method employs a plate-shaped insulator that is disposed adjacent to a plate-shaped electrode. In the method, a discharge gas containing an inert gas is supplied to a vicinity of an object to be processed from one gas exhaust port located near the plate-shaped electrode, out of at least two-line gas exhaust ports which are disposed adjacent the plate-shaped electrode. The exhaust ports are formed on opposite sides of the plate-shaped insulator and are different in distance to the plate-shaped electrode. A discharge control gas is supplied from the other gas exhaust port to the vicinity of the object. Simultaneously with the supply of the gases, electric power is supplied to the plate-shaped electrode or the object, by which plasma processing of the processing object is carried out.