To obtain three kinds of tomograms at three different X-ray energy ranges simultaneously, we have constructed a triple-energy (TE) X-ray photon counter with a cadmium telluride (CdTe) detector and three sets of comparators and microcomputers (MCs). X-ray photons are detected using the CdTe detector, and the event pulses produced using amplifiers are sent to three comparators simultaneously to regulate three threshold energies of 15, 33, and 50 keV. Using this counter, the energy ranges are 15–33, 33–50 and 50–100 keV; the maximum energy corresponds to the tube voltage. We performed TE computed tomography (TE-CT) at a tube voltage of 100 kV. Using a 0.5-mm-diam lead pinhole, three tomograms were obtained simultaneously. K-edge CT using iodine and gadolinium media was carried out utilizing two energy ranges of 33–50 and 50–100 keV, respectively. At a tube voltage of 100 kV and a current of 130 μA, the count rate was 33 kilocounts per second (kcps), and the minimum count rates after penetrating objects in TE-CT were regulated to approximately 2 kcps by the tube current.