A radiation detecting device of the present invention includes a scintillator that converts radiation into light, a substrate that supports the scintillator and includes plural sensor portions that generate charges according to the light converted by the scintillator, a thermoplastic resin layer provided on the scintillator, a first organic layer provided on the thermoplastic resin layer, and an inorganic reflection layer provided on the first organic layer. The melting start temperature of the thermoplastic resin layer is lower than the melting start temperature of the first organic layer, the scintillator includes a projection portion on a surface on the side provided with the thermoplastic resin layer, and a leading end of the projection portion penetrates the thermoplastic resin layer and makes contact with the first organic layer.