PURPOSE: To improve the operational life characteristic of a fluorescent display device, i.e., to prevent the degradation in the brightness due to operation by removing ions Al3-, Mg2+ which are electrolytes from a phosphor layer formed by electrodeposition through electrodialysis.

CONSTITUTION: A fluorescent display device is formed out of two processes: in the first process, an anodic conductor 4 and a counter electrode 7 are immersed in an electrolytic liquid 6 including phosphor powder and an electrolyte, and by providing the difference in electric potential between the counter electrode 7 and the anodic conductor 4, the phosphor powder is coated on the anodic conductor 4, and in the second process, a positive ion exchange resinous film 8 is provided between the anodic conductor 4 and the counter electrode 7, and the electric potential reverse to that of the first process is applied in the second process.