A gas laser oscillator comprising: a discharge section for exciting laser gas; a blowing section for transmitting the laser gas; and a laser gas flowing path for forming a circulation route of the laser gas between the discharge section and the blowing section, wherein the blowing section comprises: a rotary part to be rotated by a shaft driver; and a non-rotary part not to be rotated; wherein the non-rotary part includes: a casing, for holding an outer ring of a lower bearing; a stator of the shaft driver, for rotating a rotary shaft; and a spring, for thrusting the rotary shaft upward, wherein the lower bearing is directly held by the non-rotary part to contact an outer ring of the lower bearing with the non-rotary part, wherein the rotary part includes: the rotary shaft to which an impeller is mounted at an end; a rotor of the shaft driver for rotating the rotary shaft; and an upper bearing and the lower bearing coupled to the rotary shaft, characterized by an inner ring of the upper bearing being arranged rigidly press-fitted to the rotary shaft and an outer ring of the upper bearing being arranged rigidly press-fitted to a bushing, the bushing being further arranged fixed to an upper lid of an upper casing by means of bolts, and wherein the rotary part is arranged detachable from the non-rotary part by means of said bolts arranged in co-operation with the bushing, such that when bolts are removed, the rotary shaft, is facilitated to slide along a longitudinal direction thereof and, consequently, the rotary part is arranged to be taken out. a discharge section for exciting laser gas; a blowing section for transmitting the laser gas; and a laser gas flowing path for forming a circulation route of the laser gas between the discharge section and the blowing section, wherein the blowing section comprises: a rotary part to be rotated by a shaft driver; and a non-rotary part not to be rotated; a rotary part to be rotated by a shaft driver; and a non-rotary part not to be rotated; wherein the non-rotary part includes: a casing, for holding an outer ring of a lower bearing; a stator of the shaft driver, for rotating a rotary shaft; and a spring, for thrusting the rotary shaft upward, a casing, for holding an outer ring of a lower bearing; a stator of the shaft driver, for rotating a rotary shaft; and a spring, for thrusting the rotary shaft upward, wherein the lower bearing is directly held by the non-rotary part to contact an outer ring of the lower bearing with the non-rotary part, wherein the rotary part includes: the rotary shaft to which an impeller is mounted at an end; a rotor of the shaft driver for rotating the rotary shaft; and an upper bearing and the lower bearing coupled to the rotary shaft, the rotary shaft to which an impeller is mounted at an end; a rotor of the shaft driver for rotating the rotary shaft; and an upper bearing and the lower bearing coupled to the rotary shaft, characterized by an inner ring of the upper bearing being arranged rigidly press-fitted to the rotary shaft and an outer ring of the upper bearing being arranged rigidly press-fitted to a bushing, the bushing being further arranged fixed to an upper lid of an upper casing by means of bolts, and wherein the rotary part is arranged detachable from the non-rotary part by means of said bolts arranged in co-operation with the bushing, such that when bolts are removed, the rotary shaft, is facilitated to slide along a longitudinal direction thereof and, consequently, the rotary part is arranged to be taken out.