Because a restricting plate 27 is disposed using a spacer 25, an upper plate 15 is allowed to expand upward when resin is injected, but unnecessary overexpansion is restricted by the restricting plate 27. Therefore the injection of a slightly larger amount of resin 37 does not cause a distortion or breakage of the upper plate 15 and a large amount resin 37 than the predetermined amount may be injected. As a result, damage to the upper plate 15 by the injection of the resin 37 and damage to the upper plate 15, the exfoliation of the radiation sensitive layer, and the like caused by the curing of the resin 37 may be prevented and damage to the flat panel radiation detector 1 may be prevented thereby.