A cardiac function measurement system that is disposed in an extracorporeal circulator and that is configured to measure a cardiac function of a patient (P), wherein the cardiac function measurement system is configured to detect a rotation speed of a pump configured to remove blood from the patient (P) and return the blood to the patient (P), to determine a discharge pressure of the pump based on the rotation speed, to determine a withdrawal reference flow rate indicating a theoretical flow rate of the blood transferred from the pump based on the discharge pressure, characterized in that said cardiac function measurement system is also configured to determine a measured blood transfer flow rate indicating a realistic flow rate of the blood based on a measurement result of a flow rate measurement unit configured to measure a flow rate of the blood flowing through a circulation circuit of the extracorporeal circulator , calculate a difference parameter (CP) representing a difference between the withdrawal reference flow rate and the measured blood transfer flow rate , determine the withdrawal timing of the extracorporeal circulator based on the parameter (CP), and when the withdrawal timing is determined, a notification that the withdrawal timing is appropriate is displayed on a display unit. the cardiac function measurement system is configured to detect a rotation speed of a pump configured to remove blood from the patient (P) and return the blood to the patient (P), to determine a discharge pressure of the pump based on the rotation speed, to determine a withdrawal reference flow rate indicating a theoretical flow rate of the blood transferred from the pump based on the discharge pressure, to detect a rotation speed of a pump configured to remove blood from the patient (P) and return the blood to the patient (P), to determine a discharge pressure of the pump based on the rotation speed, to determine a withdrawal reference flow rate indicating a theoretical flow rate of the blood transferred from the pump based on the discharge pressure, characterized in that said cardiac function measurement system is also configured to determine a measured blood transfer flow rate indicating a realistic flow rate of the blood based on a measurement result of a flow rate measurement unit configured to measure a flow rate of the blood flowing through a circulation circuit of the extracorporeal circulator , calculate a difference parameter (CP) representing a difference between the withdrawal reference flow rate and the measured blood transfer flow rate , to determine a measured blood transfer flow rate indicating a realistic flow rate of the blood based on a measurement result of a flow rate measurement unit configured to measure a flow rate of the blood flowing through a circulation circuit of the extracorporeal circulator , calculate a difference parameter (CP) representing a difference between the withdrawal reference flow rate and the measured blood transfer flow rate , determine the withdrawal timing of the extracorporeal circulator based on the parameter (CP), and when the withdrawal timing is determined, a notification that the withdrawal timing is appropriate is displayed on a display unit. <EOS>