A radiation image detector comprises a first electrode layer, a recording photo-conductor layer, a reading charge-transportable photo-conductor layer, and a second electrode layer. The reading charge-transportable photo-conductor layer generates electric charges when being exposed to reading light. When the reading light is not irradiated, the reading charge-transportable photo-conductor layer acts approximately as an insulator with respect to electric charges having a polarity identical with the polarity of electric charges occurring in the first electrode layer and acts approximately as a conductor with respect to electric charges having a polarity opposite to the polarity of the electric charges occurring in the first electrode layer. Radiation image information is recorded as latent image charges at an interface between the recording photo-conductor layer and the reading charge-transportable photo-conductor layer.