A light source emits a laser beam to the object through an output end. An optical system is placed between the output end and the object. The optical system adjusts the energy of the laser beam emitted, through the output end, onto a unit area for a unit time. The energy of the beam spot on the object enables cutting or bending of the object. The optical system serves to adjust the energy of the laser beam irradiated to the object. The energy of the laser beam instantly changes as compared with the case where the energy of the laser beam is adjusted based on a driving voltage applied to a laser oscillator. The object is thus processed by using the laser beam with high accuracy.