To provide a method for profiling a beveling with laser spot beam which can precisely detect a welding position even at the position laving bright surroundings and has a simple structure and can precisely obtain the beveling size and the center of the beveling with a simple image processing, and to provide a device therefor.

A welding torch 12, side shifting device 14, welding carriage 16 and beveling detecting device 18 are provided. The beveling detecting device 18 is composed of a laser unit 19 and a CCD camera 20, and an axial line of an electrode 12a and the image pickup center lines of the laser spot light beam 19a and CCD camera pass through a weld position A and are positioned in the same (y)-(z) plane. The welding torch is shifted to plural (z) positions along the beveling and laterally shifted to the plural (x) positions by crossing the beveling at each (z) position, and the image of the laser spot light beam at each (x) position is picked up. The surface position (y) is obtd. by applying the image processing to this image, and the center position A of the beveling is calculated from the positions of (x), (y) and (z), and the welding torch is positioned so as to pass through the calculated center position A of the beveling at the time of welding.