A blood measurement device having high bending rigidity and having excellent propulsion properties and rotational force transmission properties in a blood vessel. A blood measurement device has a tubular shaft having flexibility, a tubular connection portion positioned coaxially with the distal end of the shaft and having an inner diameter larger than the inner diameter of the shaft, a slit communicating the inside and the outside of the connection portion, a tubular tip guide portion having flexibility coaxially connected to the distal end of the connection portion, a core material having flexibility fitted into the connection portion and extending to the distal end in the internal space of the tip guide portion to be connected to the tip guide portion, a measurement element positioned in the internal space of the tip guide portion and measuring the physical quantity of blood, and a signal wire which is extended from the measurement element to be inserted into and passed through the internal space of the shaft through the slit.