PURPOSE: To obtain an opal white glass composition for enamel having superior adhesive strength to a substrate and enabling a direct single coating by adding CoO, MnO2 or NiO to base glass contg. SiO2 and having surface properties necessary for enamelware.

CONSTITUTION: Starting materials are weighed so as to manufacture base glass having a composition consisting of, by mole, 49W64% SiO2, 3W12% B2O3, 3W 15% RO2 (TiO2+ZrO2), 22W30% R'2O [Li2O+Na2O+K2O, Li2O/(Na2O+K2O) >1] and 2W7% fluoride (expressed in terms of F2). To the starting materials are added ≤5mol% one or more kinds of oxides selected among CoO, MnO2 and NiO. They are mixed, melted by heating, rapidly cooled, and pulverized to obtain the desired opal white glass composition. Since the composition gives both ground coat enamel and cover coat enamel, when the composition is used, an opal white glass film can be formed on an iron substrate by a direct single coating.