and the t shaped noise insulation plate attaching seat 3 are attached to the stator frame 1 an acoustic absorbent 8 made of a glass wool surrounded by an acoustic absorbent scattering preventing cover 9 is installed on the stator frame 1 so as to come into contact with each other next the noise insulation plate 4 is fixed to the upper l shaped noise insulation plate attaching seat 3 a and the central t shaped noise insulation plate attaching seat 3 and is fixed to the central t shaped noise insulation plate attaching seat 3 and the lower l shaped noise insulation plate attaching seat 3 a then the bolt 7 penetrates each of holes provided in the noise insulation plate 4 and the noise insulation plate attaching seats 3 and 3 a and the bolt 7 is fixed by being fastened using the nut 5 at this time the vibration proofing rubber washer 10 is disposed between the nut 5 and the noise insulation plate 4 and the gasket 11 is disposed between the noise insulation plate 4 and the noise insulation plate attaching seats 3 and 3 a in addition the t shaped noise insulation plate attaching seat 3 may include one which extends in.