PURPOSE: To aim at automatizing a machining process, by providing a robot device for simply carrying out machinings such as, for example, chamfering, etc. in direct association with the contour of a workpiece, in a contour sensing type machining device for chamfering the top edge of a cray model for pottery so that the contour of the workpiece is directly sensed.

CONSTITUTION: In a contour sensing type machining device, a longitudinally and laterally moving rod 5 is provided on a machine frame 1, and a longitudinal servo-motor 11 and a lateral servo-motor 7, for the rod 5, are provided to the machine frame 1. A rotary spindle 15 having its front end attached with a machine tool 18, is journalled to the moving rod 5. There is provided a rotary servo-motor 23 for the spindle 15, which is associted with a signal from a workpiece side surface sensor 21 that is attached to the front end of a cross arm 19 provided to the spindle 15. Further, there is provided a resolving unit 24 which receives the rotating vector of the spindle 15 and resolves the same into a sine wave output and a cosin wave output. Further, there is provided a signal means for operating the longitudinal and lateral servo-motors 11, 17 in accordance with both outputs.