A radiation detector that includes a flexible substrate, a plurality of pixels that are provided on the substrate and each include a photoelectric conversion element, a scintillator that is laminated on the substrate, and a flexure suppression member that suppresses flexure of the substrate. When X is the size of the pixels, ZL is the limit deformation of the pixels due to flexure of the substrate, and R is the radius of curvature of flexure of the substrate caused by the weight of the scintillator, the rigidity of the flexure suppression member satisfies R ≥ X2/2ZL.放射線檢測器包括：具有可撓性的基板；設置在基板上且分別包含光電轉換元件的多個像素；層疊在基板上的閃爍體；以及抑制基板的撓曲的撓曲抑制構件。在將像素的尺寸設為X、將因基板的撓曲引起的像素的極限變形量設為ZL、將因閃爍體的重量而在基板上產生的撓曲的曲率半徑設為R時，撓曲抑制構件具有滿足R≥X2/2ZL的剛性。
