Electric field in a chamber of the surface-wave-plasma applicator was measured. Standing waves existed both above and in a chamber. However, a profile in the chamber differed from that above the chamber. This is because die profile in die chamber was affected by the chamber wall and changed to the profile decided by the geometry of die chamber. A square of the electric field strength in the chamber with plasma decreased to 1/50 of that without plasma. Almost all of die microwave power was absorbed by die plasma near the microwave window.