A blood flow measurement device comprising: a blood flow sensor comprising: a sensor portion which has a laser element generating laser light, a light receiving element receiving light, and a housing having a contact surface contacting a subject and which irradiates the subject with the laser light generated by the laser element through the contact surface, receives reflected light from the subject in the light receiving element, and outputs a signal relating to a received light amount; a holding portion holding the housing so as to be movable in a direction crossing the contact surface; a transmission portion absorbing and transmitting external force applied to the holding portion to the sensor portion; a calculation portion calculating a blood flow volume based on a signal output by the light receiving element; a storage portion; and a display portion displaying a calculation result by the calculation portion, wherein the blood flow sensor further has a pressure sensor detecting pressure applied to the contact surface from the subject, characterized in that the calculation portion acquires pressure detected by the pressure sensor at each predetermined timing stored in the storage portion, performs the calculation corresponding to the timing, and does not perform the calculation corresponding to the timing at which the pressure is acquired in accordance with a fact that the acquired pressure is not within a predetermined range previously stored in the storage portion. a blood flow sensor comprising: a sensor portion which has a laser element generating laser light, a light receiving element receiving light, and a housing having a contact surface contacting a subject and which irradiates the subject with the laser light generated by the laser element through the contact surface, receives reflected light from the subject in the light receiving element, and outputs a signal relating to a received light amount; a holding portion holding the housing so as to be movable in a direction crossing the contact surface; a transmission portion absorbing and transmitting external force applied to the holding portion to the sensor portion; a calculation portion calculating a blood flow volume based on a signal output by the light receiving element; a storage portion; and a display portion displaying a calculation result by the calculation portion, wherein the blood flow sensor further has a pressure sensor detecting pressure applied to the contact surface from the subject, characterized in that the calculation portion acquires pressure detected by the pressure sensor at each predetermined timing stored in the storage portion, a sensor portion which has a laser element generating laser light, a light receiving element receiving light, and a housing having a contact surface contacting a subject and which irradiates the subject with the laser light generated by the laser element through the contact surface, receives reflected light from the subject in the light receiving element, and outputs a signal relating to a received light amount; a holding portion holding the housing so as to be movable in a direction crossing the contact surface; a transmission portion absorbing and transmitting external force applied to the holding portion to the sensor portion; a calculation portion calculating a blood flow volume based on a signal output by the light receiving element; a storage portion; and a display portion displaying a calculation result by the calculation portion, wherein the blood flow sensor further has a pressure sensor detecting pressure applied to the contact surface from the subject, performs the calculation corresponding to the timing, and does not perform the calculation corresponding to the timing at which the pressure is acquired in accordance with a fact that the acquired pressure is not within a predetermined range previously stored in the storage portion.