To provide a plasma processing device compatible with various sizes of workpieces.

The plasma processing device M has a plurality of electrode units 10, 10 connected in a longitudinal direction. Each of the electrode units 10 has a first and a second electrode members 11, 12 with lengths corresponding to each other, a first dielectric member 13, and a pair of side frames 16. The first electrode members 11, 11, the first dielectric members 13, 13, and the side frames 16, 16 disposed on the same side in the width direction in the plurality of electrode units 10, 10 are formed in the same specifications and are connected in a longitudinal direction, respectively.