The estimated contour positions of the atrium and ventricle are obtained from multi-channel electrocardiographic waveforms. Information useful to predict the possibility of the occurrence of fatal arrhythmia, such as the position of the maximum excitation propagation point, the distribution of the late potential(LP) as an index of depolarization abnormality, and the distribution of the RT dispersion as an index of repolarization abnormality are displayed together with the estimated contour positions.