PURPOSE: To provide a plasma processor which performs uniform plasma processing to a semiconductor wafer by forming a homogeneous plasma in the vicinity of the surface of an electrode on which the semiconductor wafer is put.

CONSTITUTION: A plasma processor is equipped with a reactor 1, which forms vacuum space required for generation of plasma, an electrode 3, which is arranged inside this reactor 1 and doubles as the a placing stage to place a semiconductor wafer 2, and a plasma generator 4, which has a pair of electrodes for generating plasma in an elliptic circular region above this electrode 3, and besides it is so constituted as to apply a vertical magnetic field B to the plasma generator 4 and the semiconductor wafer 2 inside the reactor 1 by an electromagnet 5 arranged outside the reactor 1.