It is an object of the invention to provide a structure for connecting a compressor wheel and a shaft, which structure is not easily broken when rotated at high speed. A male screw is provided on an outer surface of a projection formed on the center of a rear of the compressor wheel, and a male screw is provided on a shaft. The compressor wheel and the shaft are connected with each other by a sleeve having female screws provided at each end thereof. An engagement portion is provided between the compressor wheel and the shaft.