The present invention aims to provide a working device for deburring or chamfering easily, for example on the both sides of a gear, and for desired deburring or chamfering effectively on a large-sized gear, and comprises a base stage, a workpiece hold and rotate device mounted thereon for holding and rotating a workpiece, a working device mounted on the base stage and movable to and from the workpiece and having a working tool for working against obverse and reverse sides of the workpiece, a pressing device for pressing the working device toward the workpiece, and a tracing device on the working means, composed of a workpiece obverse side tracing member corresponding to the obverse side of workpiece, and a workpiece reverse side tracing member corresponding to the reverse side of workpiece, for moving the working device in forward and rearward directions by becoming in contact with and tracing shape of the workpiece.