BLOW-BY GAS TREATMENT DEVICE FOR INTERNAL COMBUSTION ENGINE

A blow-by gas treatment device causes blow-by gas in a space defined by a cylinder head and a head cover in an internal combustion engine to flow back into an intake pipe. The blow-by gas treatment device includes a pipe joint and a blow-by gas pipe connected to the intake pipe. The pipe joint includes a basal end connected to the head cover, a distal end, a sensor-connected part connected to the pressure sensor, and a constriction located closer to the basal end than the sensor-connected part. The blow-by gas pipe is connected to a position of the pipe joint closer to the distal end than the sensor-connected part.