BLOW-BY GAS SYSTEM

This blow-by gas system is provided with: a blow-by gas flow path through which a blow-by gas discharged from an internal combustion engine passes; and an oil separator disposed midway along the blow-by gas flow path. A downstream end of the blow-by gas flow path connects to at least one of a predetermined portion of an intake passageway and a midway portion of an air introduction passageway. The predetermined portion is a portion at which at least some of the blow-by gas that has flowed into the intake passageway flows into the air introduction passageway together with an intake air in the intake passageway.