To provide an excellently economical plasma treatment apparatus capable of easily and inexpensively manufacturing various kinds of MEMS products in small quantities without a high vacuum apparatus and accompanying high maintenance work.

The apparatus comprises a combination of plasma generating electrodes 2, 3 for generating plasma discharge under atmospheric pressure, an extracting electrode 4 arranged outside the electrodes 2, 3 having openings 41, 42 for extracting plasma, and a substrate holder 6 arranged opposite to the extracting the electrode 4 and supporting a substrate 5 to be treated. The plasma generated in the electrodes 2, 3 is extracted from the openings 41, 42 in the direction of the substrate holder 6 to irradiate the substrate 5 to be treated with the plasma to form grooves 51, 52 imitating the shapes of the openings 41, 42 on the substrate 5 to be treated.