PURPOSE: To provide the possibility of direct printing on name plates, labels, etc., by irradiating the surface layer of a low thermal melting temp. of the blank material to be marked made of a synthetic resin having a two-layered structure with a gaseous laser.

CONSTITUTION: For example, the synthetic resin plate 2, 3 of the two-layered synthetic resin plate 1 formed by providing the synthetic resin plate 2 which is lower in thermal melting temp. and smaller in thickness than the synthetic resin plate 3 as a surface layer on the synthetic resin plate 3 which is relatively high in the thermal melting temp. and has a large thickness are formed respectively white and black The surface layer of such synthetic resin plate 1 which is the blank material for laser marking is irradiated with the gaseous laser subjected to data control of the output and printing characters. The pale white synthetic resin plate 2 is melted in this way and the color of the black synthetic resin plate 3 under this plate is displayed as characters.