A ceramic mirror having a maximum surface flatness of 1 .mu.m and/or a maximum centerline average height of 1 nm as measured by the laser interference method, and a method of manufacturing a ceramic mirror by compacting a titanium oxide powder having an average particle diameter no greater than 1 .mu.m and a purity of at least 99% and then sintering the compact in an ordinary, inert, vacuum, or reducing atmosphere at a temperature between 1000.degree. and 1300.degree. C. The sintering pressure may be a minimum of 50 kg/cm.sup.2. After sintering, the product may be further treated by hot isostatic pressing (HIP) in an Ar atmosphere at 1000.degree. C. and a pressure of 1800 kg/cm.sup.2. The sintered bodies are then surface ground or lapped to produce ceramic mirrors having the above characteristics for use in laser and X-ray apparatuses, cameras, and other precision optical instruments.