In a semiconductor device manufacturing apparatus which is equipped with: a process chamber; a unit for supplying gas to said process chamber; a exhausting unit to reduce pressure in said process chamber; a high frequency power source for plasma generation; a coil for generating a magnetic field; and a mounted electrode for mounting a substance to be processed, particles were transported in the circumference direction of said substance to be processed by thermo-phoretic force, by changing the magnetic field distribution, so as to make a plasma distribution at the surface of said substance to be processed, in a convex form, in ignition of the plasma or after completion of a predetermined processing, compared with the plasma distribution during said predetermined processing to said substance to be processed, and thus to generate temperature gradient of processing gas just above said substance to be processed.