A long-life electric discharge excitation excimer laser improved in that the laser gas in the laser enclosure hardly degrades, no dust enters the inside of the magnetic bearing and the inside of the motor, and damage to the portions in contact with the laser gas is little. The electric discharge excitation excimer laser is characterized by comprising a housing connected to both ends of a laser enclosure where the laser gas is sealed and a pair of main discharge electrodes are housed, a cross flow fan rotatably supported at both ends by a magnetic bearing housed in the housing and adapted to produce a laser gas flow, a motor housed in the housing and adapted to rotate the cross flow fan, a laser gas passage extending through the gap between the rotor side and the-stator side of the magnetic bearing and the gap between the rotor side and the stator side of the motor along the full length of the housing and communicating with the laser enclosure, a laser gas introduction passage extending from the inside of the laser enclosure and communicating with the laser gas passage at one end of the housing, and a filter disposed in the laser gas introduction passage.