This flow rate measurement device 1 comprises a tube 4 and a sensor unit 2 which is detachably connected to the tube 4. The tube 4 includes a transparent tube wall 41 through which blood removed from a body can be viewed from outside and a light blocking film 30 which covers a portion of the tube wall 41. A light emitting element opening 31 and a light receiving element opening 32 are formed on the light blocking film 30. The sensor unit 2 includes a light emitting element 10 which emits laser light, a light receiving element 20 which receives the laser light, and a belt 71 which detachably secures the sensor unit 2 to the tube 4. The light emitting element opening 31 is smaller than a light emitting surface 11 of the light emitting element 10. The light receiving element opening 32 is smaller than a light receiving surface 21 of the light receiving element 20. When the sensor unit 2 is secured to the tube 4 with the belt 71, the light emitting element opening 31 is included in a portion of the light emitting surface 11 and the light receiving element opening 32 is included in a portion of the light receiving surface 21. A part of the laser light emitted by the light emitting element 10 passes through the light emitting element opening 31 and enters the tube wall 41. Measurement light, which is the laser light that has passed through the light receiving element opening 32 by being reflected from the blood inside the tube wall 41 and to which the Doppler effect of the flow rate is applied, enters the light receiving element 20.Ce dispositif de mesure du débit (1) comprend un tube (4) et une unité de capteur (2) qui est reliée de manière amovible au tube (4). Le tube (4) comprend une paroi transparente de tube (41) à travers laquelle le sang évacué dun corps peut être vu de lextérieur et un film obturant la lumière (30) qui recouvre une partie de la paroi du tube (41). Une ouverture délément émetteur de lumière (31) et une ouverture délément récepteur de lumière (32)
