In the near-infrared-ray computed tomography (NIR-CT) scanner, NIR photons are produced from a light-emitting diode (LED) and detected using a visible-ray (VR) phototransistor (PT) and an infrared filter. The LED-peak wavelength is 850 nm in the living-body (LB) window range, and the penetrating NIR photons are detected using the VR PT thorough an infrared filter and a 1.5-mm-diam 15-mm-length graphite collimator. The photocurrents flowing through the PT are converted into voltages using an emitter-follower circuit, and the output voltages are sent to a personal computer through an analog-digital converter. The NIR projection curves for tomography are obtained by repeated translations and rotations of the object. The 850-nm-peak NIR photons penetrated LBs, and the NIR-CT was performed with changes in the relative sensitivities of 1 and 21.