Abstract: There is provided an oil separator for blowby gas exhibiting excellent oil separation performance in a stable manner. In a common flow path section of a gas flow passage in which the blowby gas flows and an oil passage provided with a bottom of the common flow path section where oil that has been separated from blowby gas by separation means provided midway along the gas flow passage, the width of a part of the common flow path section is regulated so as to become gradually smaller towards the bottom of the common flow path section, and a flow passage regulating section, for making part of the common flow path section that has the width regulated a restricted section, is provided so as to extend upwards from the bottom of the common flow path section.

Abstract: There is provided an oil separator for blowby gas exhibiting excellent oil separation performance in a stable manner. In a common flow path section of a gas flow passage in which the blowby gas flows and an oil passage provided with a bottom of the common flow path section where oil that has been separated from blowby gas by separation means provided midway along the gas flow passage, the width of a part of the common flow path section is regulated so as to become gradually smaller towards the bottom of the common flow path section, and a flow passage regulating section, for making part of the common flow path section that has the width regulated a restricted section, is provided so as to extend upwards from the bottom of the common flow path section.