PORCELAIN COMPOSITION

A porcelain composition which is a glass composition wherein a filler composed of at least one of Al2O3 and TiO2 is contained is characterized in that when the molar quantity of oxide Ln2O3 of rare earth element Ln is "a", the molar quantity of boron oxide B2O3 is "b" and a + b = 1 mole, "a" is within the range of 0.15-0.55 mole, "b" is within the range of 0.45-0.85 mole, oxide RO of an alkaline earth metal element R is within the range of 0.01-0.2 mole and the filler is within the range of 0.1-0.4 mole.