PURPOSE: To obtain a dental laser treatment device which is suitable for the prevention and therapy of parodontosis and alveolar pyorrhea and possesses the excellent operation performance by constituting the device so that laser beam can be radiated effectively around a tooth from a laser radiation chip in the state where a patient clamps a mouthpiece.
CONSTITUTION: The laser beam oscillated by a body device 4 is introduced into a mouthpiece 6 having a laser radiation chip 9 through a light introducing fiber 5. The mouthpiece 6 has a plurality of dummy chips 7 embedded, and is formed to the shape permitting the laser radiation chip 9 to be installed and clamped by a fitting part 8 having a hole on the part corresponding to a tooth to be treated. The laser radiation chip 9 is made of a transparent synthetic resin, and the reverse surface has a reflection part 11 for reflecting the laser beam to a radiation surface 10 side, and the laser beam is introduced from the side surface of the fiber 5.