An automatic plasma processing device having a substantially vertically disposed plasma chamber in which a plurality of semiconductor wafers can be simultaneously processed with plasma. The automatic plasma processing device comprises a container cassette adapted to contain a plurality of wafers therein, a feeding mechanism for taking out the wafers one by one from the cassette and for feeding the same, a holding frame for receiving the wafers one by one from the feeding mechanism and for holding the same therein, a driving mechanism for moving the holding frame up and down into and out of the plasma chamber, a plasma generating mechanism for generating plasma in the plasma chamber, and a control system for controlling the aforesaid mechanisms. The device is simplified in construction and can automatically and successively process a large number of wafers, while at the same time having a compact construction.