PURPOSE: To facilitate inserting and extracting of the wheel without generating eccentricity in the setting of the wheel by a method wherein an arced inflated part for obtaining an interference is formed on either one of the inner peripheral surface of a hole for the shaft of the compressor wheel or the outer peripheral surface of a turbine shaft.

CONSTITUTION: The arced inflated part 10 is formed on either one of the inner peripheral surface of the hole 6 for the shaft, whitch is formed in the compressor wheel, or the outer peripheral surface of the turbine shaft 5. When the turbine shaft 5 is fitted into the compressor wheel 1, the shaft 5 is fitted forcibly into the hole 6 for the shaft of the wheel 1 and both parts are set by force-fitting at the inflated part 10, however, in case the inflated part 10 is formed into an arced shape, inserting and extracting of both parts 1, 5 may be facilitated and the concentricity of both parts may be obtained easily since an opposing member is surely abutted against the swelled part 10 along the whole periphery thereof.