A radiation imaging apparatus includes a radiation flat panel detector configured to detect radiation incident thereupon and to generate a radiation image, a control unit configured to control a drive of the radiation flat panel detector, a heat insulation member arranged between the radiation flat panel detector and the control unit, an external housing configured to accommodate therein the flat panel detector and the control unit, a first heat transfer member configured to transfer heat from the radiation flat panel detector to a first surface of the external housing, and a second heat transfer member configured to transfer heat from the control unit to a second surface of the external housing different from the first surface.