Laser marking method and laser marking device

For distinguishable control for members such as fuel rods while following after the flow of transportation/storage/utilization, it is necessary to apply marking directly to cladding tubes. However, in a marking method for using letter pattern-masking, it is necessary to prepare and exchange various kinds of letter pattern masking corresponding to the marking letters, and the marking operation is not efficient. Then, laser beams are irradiated under focussing on the surface of an object, and the laser beams are scanned while being controlled to oxidize the surface of the object thereby applying bar code-like markings. The surface of the object at the periphery of the starting point of the laser beam scanning is coated with a mask having a predetermined thickness to conduct marking. The device can be simplified, the marking operation can be improved, occurrence of fine pores so called spikes can be prevented previously, and melting damage of the mask can be prevented since the laser beams are not focused on the surface of the mask. (N.H.)