A low thermal expansion ceramic which comprises at least one selected from the group consisting of cordierite, spodumene and eucryptite in an amount of 60 vol % to 99.9 vol % and at least one selected from the group consisting of carbides, nitrides and borides of 4a Group elements, 5a Group elements and 6a Group elements and boron carbide in an amount of 0.1 vol % to 40 vol %, and has a porosity of 0.5 % or less and a thermal expansion coefficient at 10 ° to 40 ° of 1.5 X 10-6/°C or less. The above ceramic has high rigidity and good resistance to abrasion together with low thermal expansion.