PURPOSE: To prevent printing from getting impossible due to an increase in an electric resistance, by composing return passage electrode rollers of rotatable metal cores coated with electroconductive rubber layers around which wires are wound and by setting the rollers in elastic contact with the thin electroconductive layer of discharge breakdown type recording paper.

CONSTITUTION: Pinch rollers 26, 26 are placed in elastic contact with recording paper 11 on a platen 5 by coiled springs. Levers 27, 27 are swingably supported on shafts. Two return passage electrode rollers 29 are rotatably supported on another shaft 28 at the tips of the levers 27, 27 and set in elastic contact with the recording paper 11 on the platen 5 by coiled springs 30 provided between pillars and the levers 27, 27. Each return passage electrode roller 29 comprises a metal core 31 rotatable to the shaft 28, electroconductive rubber 32 coated on the peripheral surface of the core 31 and a wire 33 spirally wound around the rubber 32.