A discharge excitation gas laser device may include a laser chamber in which a laser gas containing a halogen gas is encapsulated, a pair of discharge electrodes disposed to face each other inside the laser chamber, a fan disposed inside the laser chamber to make the laser gas flow between the pair of discharge electrodes, a motor for rotating the fan, a motor power supply for supplying power to the motor, a magnetic bearing configured to levitate the rotary shaft of the fan magnetically, a displacement sensor for detecting the position of the rotary shaft through a can, and a controller configured to measure the rotational speed of the fan on the basis of a detection signal from the displacement sensor and control the motor power supply in such a manner that the measured rotational speed becomes a target rotational speed.