To provide a technique for easily determining the failure of a pump for an artificial heart, which is desired in view of the fact that the pump, particularly of the type embedded into the body, when a patient using it is in bad health, does not make it clear whether the artificial heart or another part of the body has failed.

For the process of determining the failure of the pump for an artificial heart, if measurement data for the specific rpm of the pump being actuated are not on a 'pressure-flow' characteristic curve in Figure 1 (a), then the geometrical failure of the pump such as damage to a blade is determined to have occurred. If the measurement data are not on a 'consumed power-flow' curve, then dysemia such as thrombosis is determined to have occurred. If the data are on both curves, a failure is determined to have occurred not in the pump but in another part of the patient's body or a connection tube, etc.