A plasma processing apparatus for a very large area using a dual frequency is provided. The apparatus includes: a stage loading a substrate to be subjected to an etching or deposition process; a reaction chamber detachably coupled with the stage and having a plasma source region; a cover covering the reaction chamber; an assembly frame coupling the reaction chamber with the cover; first and second antenna sources disposed in the plasma source region, and having a plurality of antenna assemblies disposed in parallel, the plurality of antenna assemblies having a power supply connected to one side thereof and a ground connected to the other side thereof; and a plurality of magnet assemblies disposed on both sides of each antenna assembly, wherein the first and second antenna sources include m and m-1 antenna assemblies to which the same power is applied, respectively, and the antenna assemblies of the first antenna source and the antenna assemblies of the second antenna source are alternately disposed; and wherein input power applied to the first antenna source and input power applied to the second antenna source are different in magnitude and applied at the same time. Thereby, uniformity of plasma is improved to the maximum extent, so that it is possible to obtain a higher plasma density.