Provided is a corrosion device for a cylinder that can make corrosion more uniform than in the prior art and can resolve the problem of remaining corrosive liquid flowing down from a corrosive liquid supply tube. The corrosion device for a cylinder includes a treatment tank, a chuck means, at least one corrosive liquid supply tube, and a plurality of discharge nozzles that are arranged side-by-side on the corrosive liquid supply tube and are for discharging the corrosive liquid from the corrosive liquid supply tube, said corrosion device carrying out corrosion of the surface of a cylinder to be treated by means of a corrosive liquid that has passed inside the corrosive liquid supply tube and been discharged by the discharge nozzle so as to strike the surface of the cylinder to be treated. Each discharge nozzle is oriented upward at a slant with respect to the horizontal direction, and the discharge direction of the discharge nozzle is oriented toward the rotational center of the cylinder to be treated from a position that is downward at a slant from the cylinder to be treated. The discharge nozzles are provided so as to be movable closer and further away from the surface of the cylinder to be treated.