PURPOSE: To simplify the control of the position of a thermal spraying gun in relation to a thermal spray working point and to improve the efficiency of a thermal spraying work by controlling the position thereof in such a manner that the center line of the thermal spraying gun passing the thermal spray working point turns around the thermal spray working point.

CONSTITUTION: The position of the thermal spraying gun 13 passing the thermal spray working point 26a is so controlled that the central axial lie C thereof turns around the thermal spray working point 26a. More specifically, the thermal spraying gun 13 is turned in such a manner that the central axial line C passes the thermal spray working point 26a to position the top end of the gun 13 so as to face the surface of a work W perpendicularly thereto when the diameter of the work changes and the thermal spray working point 26a changes. Since there is no need for moving the work W in follow up to the top end of the gun 13 as in the prior art, the position control of the gun 13 is simplified and the efficiency of the thermal spraying work is improved.