A transparent dielectric of the <TEX>$PbO-B_2O_3-SiO_2-A1_2O_3$</TEX> system which was a low melting glass has been used for PDP (Plasma Display Panel), but it has a problem which is a reaction to be occurred between a transparent dielectric layer and electrodes (Ag, ITO) after firing. This research was conducted for ion migration of <TEX>$Ag^+\$</TEX> and <TEX>$Sn^ {2+}$</TEX> during firing three different frits of low melting glass. The result showed that yellowing phenomena occurred through a chemical reaction between <TEX>$Ag^+\$</TEX>and <TEX>$Sn^ {2+}$</TEX> at 550~58<TEX>$0^{\circ}C$</TEX> for 20~60 min. In addition, it was confirmed that the migration of <TEX>$Sn^{2+}$</TEX> from ITO electrode made a strong effect on the yellowing phenomena.