For the purpose of providing a discharge excitation type pulse laser apparatus capable of reducing disturbance of the discharge space caused by shock waves, the discharge excitation type pulse laser apparatus according to the present invention is designed for generating a pulsed main discharge by applying a high voltage between main electrodes (14, 15) including a cathode (15) and an anode (14) arranged in opposition to each other, and thereby exciting a laser gas in a discharge space (37) defined between the main electrodes to oscillate laser light (21), and characterized in that no reflector larger than a prescribed size is provided on a surface within a prescribed surface distance (LC) from the discharge space (37), and an insulating cathode insulating member (54) that is inclined such that the cathode (15) side end is highest is arranged on at least one of the upstream and downstream sides of the cathode (15) in close contact with the cathode (15).