A radiation measurement apparatus includes an array-type radiation detector and an information calculation unit which obtains information on energies detected by pixels of the detector and information on a pixel on which a radiation ray is incident. The information calculation unit includes an energy conversion unit which converts a detected signal of a pixel which is equal to or larger than a predetermined threshold value into a detected energy value, a judgment value calculation unit which obtains a judgment value used to judge whether Compton scattering has been generated in the pixel in accordance with the detected energy, a judgment unit which judges whether the Compton scattering has been generated in the pixel in accordance with the judgment value, and a determination unit which obtains information on a pixel on which a radiation ray is first incident in accordance with a result of the judgment performed by the judgment unit.