An electric supercharger includes an electric motor, a compressor wheel rotated by the electric motor, and a compressor housing. The compressor housing includes a first passage through which air is introduced, an introducing port connecting to an EGR device, a second passage through which at least one of air and EGR gas is flowed, a bypass passage through which at least one of air and EGR gas is flowed, and a bypass valve to open and close the bypass passage. When the bypass valve is opened, air introduced from the first passage and EGR gas introduced from the introducing port are flowed through the bypass passage to the internal combustion engine. When the bypass valve is closed, air introduced from the first passage and EGR gas introduced from the introducing port are compressed in the compressor wheel and flowed through the second passage to the internal combustion engine.