In magnetocardiography, an assisting technique for a doctor diagnosing a heart disease will be provided. In the magnetocardiography, magnetism to be generated from a subject's heart is measured by a magnetic sensor, and from this measured data, a position of center of gravity of excitement wave front in a cardiac muscle excitement propagation process and a transition vector (wave front vector) is calculated by an analyzing computer. With this wave front vector as a feature parameter, the Mahalanobis' distance is calculated from a data base obtained by diagnosing in the past, a possibility (probability) of the subject having a heart disease is presumed on the basis of the Bayes' theorem for displaying. Also, by superimposing on a heart picture, the wave front vector position is displayed, and a cluster classification position in the wave front vector is displayed. Also, by the similar retrieval, another subject extremely similar to the subject in the feature parameter will be retrieved from the data base for screen displaying.