Disclosed is a method of manufacturing a flat panel detector such that the surface on the side of a fluorescent body layer of a scintillator panel which has the fluorescent body layer comprising a column crystal on the supporting body, is coupled to the planar light receiving element surface of a light-receiving element, comprising: a step of manufacturing the scintillator panel which has a larger area than that of the planar light receiving element surface; a step of trimming the edges of the scintillator panel, obtained by the step of manufacturing the scintillator panel, to correspond to the area of the planar light receiving element surface; and a step of coupling the edge-trimmed scintillator panel to the planar light receiving element surface, thus providing a flat panel detector which has an excellent productivity and that can be made small in size without non-image area.