A cogeneration system comprising: an intake pipe one end of which communicating with outside air and another end of which being connected to an engine, the intake pipe having a motor accommodating part, a mixer accommodating part and an impeller accommodating part; a mixer disposed in the mixer accommodating part of the intake pipe to supply gas into the intake pipe; and an intake compressor for compressing a mixed gas which is a mixture of the air and the gas; wherein the intake compressor comprises: a motor disposed in the motor accommodating part of the intake pipe; and a compressor impeller disposed in the impeller accommodating part of the intake pipe and rotated by the motor to compress the mixed gas, wherein the mixer is positioned between the motor and the compressor impeller in the intake pipe, and wherein the motor is disposed upstream of the mixer, wherein the mixer comprises: an acceleration unit for reducing a cross-sectional area of the mixer accommodating part while progressing toward the compressor impeller from the motor; and a spray unit having a smaller cross-sectional area than the acceleration unit and provided with a spray hole connected to a gas intake pipe of the intake pipe, wherein the intake compressor further comprises a shaft connecting the motor and the compressor impeller, wherein the spray unit and the acceleration unit are disposed to surround the shaft, wherein the spray unit is disposed closer to the compressor impeller than the acceleration unit. an intake pipe one end of which communicating with outside air and another end of which being connected to an engine, the intake pipe having a motor accommodating part, a mixer accommodating part and an impeller accommodating part; a mixer disposed in the mixer accommodating part of the intake pipe to supply gas into the intake pipe; and an intake compressor for compressing a mixed gas which is a mixture of the air and the gas; wherein the intake compressor comprises: a motor disposed in the motor accommodating part of the intake pipe; and a compressor impeller disposed in the impeller accommodating part of the intake pipe and rotated by the motor to compress the mixed gas, wherein the mixer is positioned between the motor and the compressor impeller in the intake pipe, and wherein the motor is disposed upstream of the mixer, a motor disposed in the motor accommodating part of the intake pipe; and a compressor impeller disposed in the impeller accommodating part of the intake pipe and rotated by the motor to compress the mixed gas, wherein the mixer is positioned between the motor and the compressor impeller in the intake pipe, and wherein the motor is disposed upstream of the mixer, wherein the mixer comprises: an acceleration unit for reducing a cross-sectional area of the mixer accommodating part while progressing toward the compressor impeller from the motor; and a spray unit having a smaller cross-sectional area than the acceleration unit and provided with a spray hole connected to a gas intake pipe of the intake pipe, an acceleration unit for reducing a cross-sectional area of the mixer accommodating part while progressing toward the compressor impeller from the motor; and a spray unit having a smaller cross-sectional area than the acceleration unit and provided with a spray hole connected to a gas intake pipe of the intake pipe, wherein the intake compressor further comprises a shaft connecting the motor and the compressor impeller, wherein the spray unit and the acceleration unit are disposed to surround the shaft, wherein the spray unit is disposed closer to the compressor impeller than the acceleration unit.