A turbocharger including a compressor housing, a flange, an air bypass valve and a seal. The compressor housing has an impeller housing, an upstream passage positioned upstream of the impeller housing and a downstream passage positioned downstream of the impeller housing. The flange is coupled to the compressor housing and has a bypass passage connected to the downstream passage of the compressor housing and the upstream passage of the compressor housing. A groove is formed at a surface of the flange opposing the compressor housing and the seal is fitted into the groove. Therefore, a tight seal of the flange and the compressor housing can be ensured by the seal. Further, the air bypass valve is coupled only to the flange. Therefore, a tight seal of the turbocharger can be ensured easier than in a case where the air bypass valve is coupled over the flange and the compressor housing.