A radiation imaging device according to one embodiment includes a radiation detection panel having a first surface on which a detection region is formed and an electrode pad is formed outside the detection region, and a second surface on a side opposite to the first surface, a base substrate having a support surface configured to face the second surface of the radiation detection panel and configured to support the radiation detection panel, and a flexible circuit substrate connected to the electrode pad via a connecting member, wherein an end portion of the base substrate is located further inward than an inner end portion of the connection region in which the electrode pad, the connecting member, and the flexible circuit substrate overlap each other when seen in an Z direction orthogonal to the support surface.