PURPOSE: To prevent application unevenness of a phosphor coating formed using aqueous phosphor application liquid.

CONSTITUTION: When a phosphor coating formed by using aqueous phosphor application liquid is applied, air bubbles are produced in the liquid so that inferior appearance is caused easily by application unevenness. The present invention sues a thickner having large molecular weight of 4-10 million for ethylene oxide used in aqueous phosphor application liquid produces aqueous phosphor application liquid of 0.05-2.0weight% as mixing ratio with respect to the phosphor of the thickener and uses these. In the produced aqueous phosphor application liquid,air bubbles produced by air blow burst easily after its application in comparison with conventional aqueous phosphor application liquid, thereby application inferiority by the bubbles is deleted.