A radiation detection device includes: a radiation detection panel; a supporting member having a first surface and a second surface being opposite to the first surface, wherein the radiation detection panel is provided at a side of the first surface; first and second power supply units that supply operating electric power of the radiation detection panel; a housing that accommodates the radiation detection panel, the supporting member, and the first power supply unit; and a holder portion which is provided on the second surface of the supporting member and to which the second power supply unit is detachably attached, the holder portion includes a pair of frames that protrude toward a bottom of the housing which faces the second surface of the supporting member and a concave portion as defined herein, and the bottom of the housing has an opening portion through which the concave portion is exposed.