A magnetic field distribution measurement device (1) provides a non-contact magnetic field measurement on a subject's chest at a plurality of coordinates and forms therefrom time-series magnetic field distribution data. A first arithmetic device (2) in response generates image data representing a three-dimensional, intramyocardial current density distribution. A second arithmetic device (3) receives a plurality of tomographic image data separately obtained by a tomographic diagnosis apparatus and processes the data to generate three-dimensional, anatomical image data. A display device (4) receives these data and displays on an anatomical image an image representing an intramyocardial current density. This can facilitate identifying an anatomical, positional relationship of an abnormal, electrical reentry circuit caused in heart muscle. Furthermore, the anatomical image may be replaced with an image representing a normal stimulation propagation circuit and serving as a template.