PROBLEM TO BE SOLVED: To provide a pressure detection part capable of controlling growth of thrombi in blood in the process of extracorporeal circulation by forming the pressure detection part in a shape with reduced blood retention parts as much as possible.SOLUTION: The pressure detection part includes: two connection parts 7a and 7b to be connected to an extracorporeal circulation circuit to exctracorporeally circulate the blood of a patient and a response part 7c disposed between the connection parts to be displaced in the radial direction according to the pressure in the extracorporeal circulation circuit. The cross section in the radial direction of the response part 7c and the connection parts 7a and 7b is circular or oval. The inner diameter of the response part 7c is larger than the inner diameter of the connection part 7a or 7b. The connection part 7a or 7b has a tapered surface 7aa or 7ba inclined in such a way that the inner diameter becomes gradually larger toward the response part 7c.
