Provided is a manufacturing process of a rare earth activated alkaline earth metal fluorohalide stimulable phosphor exhibiting improved productivity accompanied with an X-ray resistance property against repeating use upon X-ray exposure. Also disclosed is a liquid phase manufacturing process of a rare earth activated alkaline earth metal fluorohalide stimulable phosphor represented in following Formula (1) possessing the steps of adding an aqueous solution containing inorganic fluoride into a reaction mother liquor in which barium halide is dissolved at a reaction temperature of 85-100.degree. C., to form a crystalline precipitate of a precursor of a rare earth activated alkaline earth metal fluorohalide stimulable phosphor, and removing a solvent from the reaction mother liquor, wherein a precursor of a stimulable phosphor is prepared via the foregoing steps conducted in parallel. Ba.sub.(1-x)M.sup.2.sub.(x)FBr.sub.(y)I.sub.(1-y):aM.sup.1, bLn, cO Formula (I)