PURPOSE: To provide glass flux having low thermal expansion, capable of providing surface gloss and carrying out muffle painting without generating crack in ceramic products.

CONSTITUTION: This glass flux is obtained by melting, cooling and solidifying glass raw materials mixed so as to contain 1-10wt.% of Li2O, 5-35wt.% of Al2O3, 15-65wt.% of SiO2, 20-60wt.% of PbO and 1-30wt.% of TiO2 and pulverizing the mixture. The glass flux contains preferably lead titanate crystals, β-spodumene crystals or β-eucryptite crystals, etc. A coloring raw material such as pigment or paint for ceramics i s preferably added to the glass flux.