The superior ablation ability of the Erbium : YAG laser (Er : YAG laser) for hard tissue has recently become clear, and it might have some potential as a hard tissue cutting device under endoscopic application, because the laser energy of the Er : YAG can be transmitted through a special fiber. However, the action of this laser wavelength in bone is basically a photothermal effect, so before using this Er : YAG laser system clinically, it is necessary to assess the degree of heat which it generates in cutting target bone. We cut lower jaw of a pig with a conventional turn cutting diamond bar and then with the Er : YAG laser energy and measured the heat generated. It was significantly low in the Er : YAG laser compared with the conventional turn cutting apparatus. These features suggest that the Er : YAG laser has potential for application as a bone cutting device available for use in minimally aggressive spinal surgery.