To improve operation rate of a plasma source by making a replacement cycle of a deposition-preventive plate long.

A plasma source 1 includes: a plasma generating container 2 which has a cooling mechanism and into which gas for plasma generation is introduced; a deposition-preventive plate 5 which is arranged inside the plasma generating container 2; and a plurality of permanent magnets 3 for cusp magnetic field generation which are arranged outside the plasma generating container 2. In a position opposed to a permanent magnet 3 across a wall surface of the plasma generating container 2 in the inside of the plasma generating container 2, a magnetic material 4 is provided which is arranged abutting on the inner wall surface of the plasma generating container 2.