The invention relates to a treatment device for workpieces, having the following: a treatment chamber (1); a shaft (2) which extends through a wall of the treatment chamber (1) into the treatment chamber and which is mounted in a rotatable manner; an electric treatment unit (3) which is secured to the shaft (2); and a power supply arrangement (6) with a first supply line (61), an electric coupling (63, 64), a second supply line (62), and an actuating unit (7). The electric coupling (63, 64) has a first coupling element (63), which is secured to the shaft (2) outside of the treatment chamber (1), and a second coupling element (64). The first supply line (61) connects the electric treatment unit (3) to the first coupling element (63), and the second supply line (62) is connected to the second coupling element (64). The actuating unit (7) is designed to actuate the coupling (63, 64) in order to bring the second coupling element (64) into contact with the first coupling element (63) or release the second coupling element (64) from the first coupling element (63).