Abstract: A radiation detection device is provided that is wide in visual field, wide in application range of radiation energy, and which is smaller and lighter in weight as compared to other devices. The device includes a detecting element group has a plurality of detecting elements that detect radiation are three-dimensionally arranged. The detecting element group has a structure with a depletion formed by removing the detecting element at any position from a virtual detecting element group in which the detecting elements are laid out on any virtual surface. The depletion is provided at a position at which a difference of detected values between one detecting element and another detecting element arranged along any direction exhibits different values in a case where the radiation having the direction as an incident direction enters and a case where the radiation having an opposite direction of the direction as an incident direction enters.