PURPOSE: To obtain a fluorescent screen suitable as the output screen of a fluorescent X-ray multiplying tube by depositing a phosphor only on the phosphor- film-attached area of a base plate through electrodeposition after covering the said base plate with a tool.

CONSTITUTION: A circular electric-field-correction conducting part 10 is provided around the phosphor-film attached area, an effective surface (A), of a tool 9, with a given distance allowed between the surface (A) and the conducting part 10. Here, the surface of the tool 9, except the condcting part 10, is coated with an insulating film 11. After that, electrodeposition is carried out by covering a base plate 5, on which a conductive film 6 made of In2O3 or the like is formed beforehand, by use of the tool 9 so as to form a phosphor film 8 only on the effective area (A). By the means mentioned above, the work efficiency is notably enhanced since conventionally performed trimming becomes unnecessary. In addition, the acvantage is that the thickness of the phosphor film 8 thus formed is homogeneous.