To provide a milk component continuous measurement device continuously measuring the components contained in milk in milking.

This milk component continuous measurement device is provided with an incident window part of light transmitting performance, a liquid retention part surrounded with an inner wall face of light transmitting performance excluding the incident window part, a liquid feeding means feeding liquid containing milk component in the liquid retention part, an outlet opened in the upper part of the liquid retention part, an overflow channel discharging bubbles from the liquid retention part along with the liquid flowing from the liquid retention part via the outlet, a liquid storage part communicated with the overflow channel and storing the milk component contained liquid overflowed from the liquid retention part, a light source light irradiating the milk component contained liquid being present in the liquid retention part via the incident window, part an optical receiver receiving the light transmitting the milk component contained liquid without absorbed in the components of the milk component contained liquid in the liquid retention part, a computing means finding absorption rates according to respective wavelengths based on the light receiver signals from the light receiver and finding concentrations of a plurality of components contained in the milk component contained liquid based no the obtained absorption rates respectively, and a display means displaying the concentrations of the plurality of components obtained by the computing means.