There is provided a radiation image conversion panel having strong resistance to physical impact, and in which enhanced sharpness and adhesion are balanced, especially, enhanced adhesion of a photostimulable phosphor layer onto a support is achieved, and a preparation method of the radiation image conversion panel. The radiation image conversion panel comprising on a support a sublayer and at least one photostimulable phosphor layer in this order from the support, featured in that the photostimulable phosphor layer is formed by a gas phase method and has a thickness of not less than 50 μm, and the sublayer comprises a thermoplastic resin and the thickness of the central portion in an image area of the sublayer is greater than that of the peripheral portion of the image area.