There is provided a processing apparatus including a holding table having a holding surface for holding thereon a workpiece with a plurality of devices formed in respective areas demarcated on a face side of the workpiece by a plurality of projected dicing lines, a processing unit that processes the workpiece held on the holding table, an image capturing unit that captures an image of the workpiece held on the holding table, a moving unit that moves the holding table relatively to the processing unit and the image capturing unit in horizontal directions along the holding surface, a touch panel that displays thereon the image captured by the image capturing unit, and a control unit. The control unit detects a line in an image positioned within an allowable region based on a contact line traced on the image displayed on the touch panel and registers the detected line.