The invention proposes a device for measuring the pressure of blood in a pipe (44) of an extracorporeal blood circuit (42) includes a pressure measurement section (46) having a substantially rigid wall (64) including a hole (66) which is sealed by a closure element (68), the internal face (70) of which is in contact with the blood and the external face (72) of which is in contact with the ambient air, it being possible for the closure element (68) to be elastically deformed overall along a deformation axis (A—A) under the effect of the blood pressure. The closure element (68) is made in a single piece with the associated rigid wall (64) of the pressure measurement section (46).