New ceramic endoprobes are able to contact with the aimed lesion during Nd-YAG laser exposure with water infusion and durable by irradiation under the power of 30 W within 2 seconds. Endoscopic laser hyperthermia was carried out with endoprobe (wide divergent micro rod) and thermosenser through the 2 channel upper GI endoscope(GIF-2T). According to histological studies, wide superficial mucosal damage appeared under the power of 5 W keeping the temperature at 42.0±1.0°C for 10 minutes. Maintenance of the temperature at the therapeutic level in the canine stomach by foot switch of Nd-YAG laser was not easy. This is the first report that the computed thermo-system is newly developed. Also, farther studies to find out the sutable factors for endoscopic hyperthermia will be made in the near future.