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; an electronic component that is provided on the second surface of the supporting member and drives the radiation detection panel or processes an electric signal output from the radiation detection panel; and a housing that accommodates the radiation detection panel, the supporting member, and the electronic component, a bottom of the housing which faces the second surface comprises a flat portion and a slope portion that is adjacent to the flat portion and becomes closer to the second surface as becoming further away from the flat portion, and the electronic component is provided at a position as defined herein.