formed however the curved engagement claws 81 may be separate members which are fixed to the inner ring portion 74 by welding it is to be noted that in the case of welding or the like of the engagement claws it may take a structure in which the engagement claws 81 are overlapped on the inner ring portion 74 and then welded the methods of provision of the engagement claws described above are the same as in the modification examples shown in fig4 a and 4 b and fig5 fig3 b shows an engagement state of the inner ring portions 74 a and 74 b when a pair of the two divided stator blades 72 is coupled as shown in the figure the pair of the two divided inner ring portions 74 a and 74 b are engaged with the engagement claws 81 and the rigidity against the deflection from the upper side to the down side of the drawing is improved it is to be noted that if it is designed such that the engagement claws are disposed to the lower side of the inner ring portion 74 the rigidity against the deflection from the lower side to the upper side of the drawing may also.