To provide a blow-by gas recirculation device capable of preventing freezing with a simple structure.

A blow-by gas recirculation device re-circulates blow-by gas to a suction side through a gas recirculation pipe 31. An intermediate section of the gas recirculation pipe is arranged at a position higher than a gas in-flow section 31a and a gas out-flow section 31b at both ends. A diaphragm 33c comprising a through hole with a cross section area smaller than that of the gas recirculation pipe is provided to a plate material whose plate face is arranged in the gas recirculation pipe in a vertical direction, at the intermediate section of the gas recirculation pipe.