1. An electrical impedance measuring apparatus comprising: a plurality of electrodes which are adapted to be adhered to a periphery of a chest of a living body; a potential measurer which is configured to perform a process of applying a current to any ones of the electrodes, and measuring potentials by means of other electrodes, on all of the electrodes while changing the electrodes to which the current is to be applied; an impedance acquirer which, based on the applied current and the potentials measured by the potential measurer, is configured to obtain an impedance of each of a plurality of meshes, a chest section being divided into the meshes; a histogram producer which is configured to set, in the chest section, at least one region of interest (ROI) including a region from a ventral side to a dorsal side, and which is configured to obtain a histogram of an impedance distribution in the ROI; a producer which is configured to produce a color impedance distribution map in which amplitudes of the histogram are replaced with corresponding colors; a curve producer which is configured to produce a displacement curve of a centroid, the displacement curve connecting together centroids of impedance distributions that vary with time in the ROI; and a display controller which is configured to cause the displacement curve to be displayed.