PURPOSE: To simplify a control device by supporting a rotary rod fitted with a marking tool at the tip with an articulate linkage rotatably in all directions, arranging one end of the rotary rod in a housing, connecting the end section of the rotary rod to a pair of expandable jacks, and controlling the direction of the longitudinal axis of the rotary rod.

CONSTITUTION: A fine impact type marking tool 2 is fitted to one end in the direction of the longitudinal axis of a rotary rod 1. The other end of the rotary rod 1 is arranged in a fixed housing 4 and is supported by an articulate linkage 5 at the opening 4a of the housing 4 so that the longitudinal axis can be rotated in all directions. A pair of expandable jacks 6 are arranged via ball joints 7 in parallel to the rotary rod 1 in the housing 4. The jacks 6 and the rotary rod 1 are connected by the ball joints 7 and arms 9. The direction of the longitudinal axis of the rotary rod 1 is controlled by the jacks 6.