To prevent a compressor from getting damaged by moisture when the water for cooling an intake air is jetted.

This internal combustion engine with a supercharger comprises an intake throttle valve 14 installed in an intake passage 9 on the downstream side of the compressor 5 of a supercharger 3, a bypass passage 50 allowing the intake passage between the compressor and the intake throttle valve to communicate with the intake passage on the upstream side of the compressor, a bypass valve 51 opening and closing the bypass passage according to the intake passage internal pressure on the downstream side of the intake throttle valve, a water jetting valve 53 jetting the water for cooling the intake air into the intake passage between the compressor and the intake throttle valve, and a gas-liquid separator 52 separating the moisture contained in the intake air flowing in the bypass passage. When the bypass valve is opened immediately after the intake throttle valve is suddenly closed, and the intake air is returned to the upstream side of the compressor through the bypass passage, the water droplets in the intake air is separated by the gas-liquid separator. Since the water droplets in the intake air is returned to the upstream side of the compressor and adhered to the compressor, the compressor can be prevented from being corroded or damaged.

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