Low thermal expansion ceramics have been required for ultra precision nanometer positioning stage in the semiconductor equipments. Especially pore-less advanced ceramics have been playing an important part as mirror materials in the optical equipments. Nippon Steel produces Sialon and NEXCERA as the solutions for these demands. Sialon based on silicon nitride shows a thermal expansion of 1.3 x 10-6/K with a high Young's modulus of 300GPa. Newly-developed NEXCERA based on cordierite ceramics shows near-zero thermal expansion around the room temperature with a Young's modulus of 130GPa. For these advanced ceramics, near-net shape sintering, direct bonding and mirror polishing are available. These technologies will provide us new design possibilities in precision engineering fields like optical system.