We observed nerve excitations on bullfrog sciatic nerves by an optical stimulation using a Holmium YAG (Ho:YAG) laser with the laser power over 2.0 [W]. The laser power was higher the amplitude of the action potential was bigger. However, when the laser power over 10.0 [W], the laser gave damage to the sciatic nerve and the action potential decreased. Not only the action potential was evoked by the high temperature but also the sciatic nerve was damaged by an overlarge temperature. These results show the possibility that the single wavelength laser can use to position estimation of epileptogenic focus and irreversible blocking of propagation of epilepsy seizure.