PURPOSE:To easily form various surface conditions corresponding to the kind of coating material, by contacting gas or liquid which transmits the light and also, brings on a chemical change at a fixed temperature on the surface of material to be processed and then, irradiating laser light on its surface. CONSTITUTION:The material to be processed 5, such as metals, ceramics, semiconductor etc., is placed in the closed vessel 1 and pre-treatment is carried out cleaning the surface by irradiating laser light from the laser irradiating apparatus 4 through coating material. Gas or liquid of halogen compound transmitting the laser light and bringing on a chemical change (thermal decomposition) at more than a fixed temperature, is used for the above-mentioned coating material through the entrance opening 2 and the exit opening 3. Next, the laser light is irradiated on a fixed place of the surface after carrying out the above-mentioned coating on the surface of the material 5 and corrosive action is carried out on the surface of the material 5 at more than a fixed temperature. The surface is able to process accurately by various process in a wide extent by combining the coating material and laser light.