The invention relates to a method for laser-beam welding a first material in the form of a thermoplastic polymer material with a second material, which is transparent for a used laser light, wherein the inventive laser-beam welding method consists in orienting the laser beam towards the first material (A) to a welding point through the second material and in softening at least the first material at the welding point by means of the laser light. The aim of said invention is to remove disadvantages of known additives used for the laser-beam welding and to deliver novel additives, which are differently usable for different wavelengths of the laser light, are not toxic, provided with a neutral and stable colour, are heat-resistant, inexpensive, compatible with plastic material and low-affecting the physical properties thereof. For this purpose, said first material comprises from 0.001 to 20 % by weight one or several types of metal phosphate and/or metal phosphite.