A radiation detector including: a substrate formed with plural pixels that accumulate electrical charges generated in response to light converted from radiation in a pixel region at an opposite-side surface of a base member to a surface including a fine particle layer; the base member being flexible and is made of resin and that includes a fine particle layer containing inorganic fine particles having a mean particle size of from 0.05 μm to 2.5 μm, a conversion layer provided at the surface of the base member provided with the pixel region and configured to convert the radiation into light; and a reinforcement substrate provided to at least one out of a surface on the substrate side of a stacked body configured by stacking the substrate and the conversion layer, or a surface on the conversion layer side of the stacked body.