To prevent floating dust and reaction product from attaching to an inner wall of a chamber, and prevent dust deposited in an inner wall of a chamber from removing and attaching to a semiconductor board in a plasma treatment device for etching and film formation treatment.

An electrostatic electrode board 1 which is arranged in contact with an inner wall of a chamber 2 and is constituted to hold a conductive board 1a between insulation films 1b is provided, a DC voltage is applied to the conductive board 1a and floating dust 14 and reaction product 13 are drawn and attached to the electrostatic electrode board 1. An application voltage is made a reverse voltage by a switch mechanism 4 during chamber cleaning, and the attaching floating dust 14 and reaction product 13 are removed.