A method for manufacturing a radiation image conversion panel which comprises the steps of: effecting aggregate reduction for a calcined product of a stimulable phosphor by dispersion in a dispersion medium, to thereby obtain a slurry; removing grains therefrom that are of at least a predetermined size by wet classification; thereafter adding a binder, with the dispersion medium being substituted by a solvent when necessary, to thereby prepare a phosphor layer coating material; and subsequently applying the coating material onto a surface of a support and drying.