PURPOSE: To evenly and continuously etch one side of a plate material with high productive efficiency by eccentrically rotating the plate material with the surface to be etched directed downward, continuously moving the material, and injecting a liq. etchant onto the surface from the lower part.

CONSTITUTION: A series of plate materials 1 having the shape of a circle, a square, etc., are freely detachably fixed to the plates 2. The plate 2 is eccentrically fixed to the rotating shaft 3 having a gear 6, and the rotating shaft 3 is fixed freely rotatably to a conveyor means of an endless belt. The plate 2 is horizontally conveyed by the conveyor means, and the gear 6 is engaged with a rack 9 for stopping and moving the gear 6 and rotated around the rotating shaft 3. As a result, the plate material 1 is eccentrically rotated with the surface to be etched directed downward, and horizontally and continuously moved. A liq. etchant is injected onto the side to be etched of the moving plate material 1 from the lower part by a spray nozzle 5, and the one side is etched.