A single flat panel detector provides radiation images which can correspond with various radiographic modes. In a radiation imaging apparatus including a flat panel detector which derives a radiation image according to incident radiation, a holding unit which holds the flat panel detector and a connecting mechanism capable of performing a connecting and a disconnecting between the holding unit and the flat panel detector, the flat panel detector can be controlled so that the maximum number of radiation images that the flat panel detector can derive when the flat panel detector is disengaged from the holding unit is smaller than the maximum number of radiation images that the flat panel detector can derive when the flat panel detector is held by the holding unit.