A radiation image storage panel comprises a substrate, a stimulable phosphor layer, which is constituted of a stimulable phosphor, and a transparent water vapor proof film, which is constituted of a water vapor proof layer and a transparent thin film. The substrate, the stimulable phosphor layer, and the transparent water vapor proof film are overlaid in this order. The transparent water vapor proof film is overlaid via an adhesive layer on the stimulable phosphor layer. The transparent thin film has a thickness falling within the range of 1 .mu.m to 10 .mu.m. The radiation image storage panel has good water vapor proof characteristics and is capable of yielding an image of good image quality with a high sensitivity.