PROBLEM TO BE SOLVED: To provide a living body magnetic field measuring apparatus capable of visualizing the electric current distribution within a cardiac muscle according to a heart figure. SOLUTION: A magnetic component in the z direction perpendicular to the breast plane is measured from two directions of the front plane 17 and the rear plane 18 of a breast portion, and the electric current distribution and the intensity distribution of the electric current distribution in the two direction are calculated. A three dimensional standard model are made according to the average data relating to the heart figure of a healthy person, and position alignment is performed using the coordinate of a nodus sinuatrialis and the coordinate of a left ventricle region. In a set boundary 20, a weighting factor is calculated in which the electric current distribution and the intensity distribution of the electric current distribution in the front plane and the rear plane of the breast portion best coincide, after correcting an electric current level, the electric current distribution and the intensity distribution of the electric current distribution in the two direction are projected to the three dimensional standard model to obtain the three dimensional display of an electric current distribution image within the cardiac muscle. A white region 31 with the small intensity of an electric current vector, a gray region 32 with the middle intensity of the same, and a black region 33 with the large intensity of the same, and electric vectors 30 are displayed on the standard model 29 after the position alignment. COPYRIGHT: (C)2005,JPO&NCIPI