To provide a device and a method for laser beam working, which cope with the dimensions of an object to be worked, and by which laser beam working with high productivity and efficiency is performed.

In a laser beam working device, respective laser beam 2a, 2b obtained by branching a laser beam 2 by a branching means, which is emitted from a laser beam oscillator 1, are guided to the working positions of an object 7 to be worked by respective scanning means 4, 5. By irradiating the object 7 with the respective laser beams 2a and 2b focused by focusing means 6a and 6b, laser beam working is performed to working areas B in prescribed ranges on the object 7 by the respective laser beams 2a, 2b. By moving relatively the object 7 to the respective focusing means 6a and 6b, the following working areas are subjected to the laser beam working successively by respective laser beam 2c, 2c emitted from the respective focusing means 6a, 6b. In this case, an adjusting means 10 is provided, which adjusts automatically an interval C between the center points of the respective focusing means 6a, 6b according to the size of the whole working area A on the object 7.