To obtain a composition having improved heat resistance and excellent surface smoothness by including SiO2, B2O3, Al2O3, MgO, CaO, SrO, BaO and Ta2O5 as oxides in a specific weight ratio.

The composition consists of 45-65% SiO2, <10% B2O3, ≤25% Al2O3, 0.1-10% MgO, 1.0-25% CaO, ≤25% SrO, ≤40% BaO and 0.1-25% Ta2O5 and ≥90%, preferably 100% except inevitable impurities in total of each component. Further a fluoride such as CaF2, a sulfate such as Na2SO4 and a clarifying agent such as As2O3 are added if need in a melting process. Particularly by including 8-15% CaO, 1-7% SrO, 0.1-5% MgO, 7-13% BaO, the composition excellent in heat resistance, improved in deformation point to ≥830°C, having excellent matching of thermal expansion to a ceramic substrate and excellent defoaming property and line property is obtained.