A stimulable phosphor panel comprises a substrate having rigidity, a stimulable phosphor layer, and a transparent water vapor proof cover, which are overlaid one upon another in this order. The stimulable phosphor layer is accommodated and sealed within an enclosed region, which is enclosed between the substrate and the transparent water vapor proof cover. An expansible and contractible buffer space is formed so as to be in communication with the enclosed region. The buffer space has a volume falling within the range of 1/10 times to two times as large as the volume of the space within the enclosed region. The transparent water vapor proof cover may be constituted of a deformable film, and the buffer space may be formed by the utilization of a certain area of the transparent water vapor proof cover.