In a radiation-image conversion panel, a fluorescent layer containing a phosphor and a protective layer are formed on a support in this order. The protective layer has a water-vapor transmission rate of 1 g/m.sup.2/24 h or lower at 40.degree. C. and a reflectance of 3% or lower at a wavelength of light emitted from the phosphor. In addition, the protective layer may be obtained by attaching a removable film to a thin transparent film so as to produce a laminated film, forming a vapor-barrier layer on an exposed surface of the thin transparent film by vacuum deposition so as to produce a moisture-resistant film, placing the moisture-resistant film on the fluorescent layer, and removing the removable film from the moisture-resistant film.