A cardiac function variation evaluation apparatus includes: a continuous flow type auxiliary artificial heart 20 connected to a ventricle (10A); a pressure sensor 30 for detecting ventricle (10A) internal pressure; and means (a personal computer 40) for evaluating contractile variation of the ventricle, to which the auxiliary artificial heart 20 is connected, based on internal area APMp of a closed-loop of a relationship between the ventricle internal pressure detected by the pressure sensor 30 and a consumption power of the auxiliary artificial heart 20. Thus, the contractile variation of the ventricle, to which an auxiliary artificial heart is connected, can be continuously evaluated not by use of an ultrasonic echo apparatus or a conductance catheter but by use of a non-invasive method.