A laser type ignition device for an internal combustion engine includes a laser oscillator mounted in the internal combustion engine so as to focus its laser beam on an air-fuel mixture supplied into the combustion chamber, a pressure sensor for detecting pressure in the combustion chamber, a power source for the laser oscillator and a control unit for controlling the power source to supply the laser oscillator with the current whose amount changes according to the pressure in the combustion chamber. The power of the laser beam increases as the pressure in the combustion chamber decreases to completely ignite the air-fuel mixture.