Optical ceramics such as fused silica and transparent alumina are expected to play an important role in nuclear systems under development. For example, optical diagnostics of burning fusion plasma will be crucial for success of the ITER. The paper will describe behaviors of radiation induced luminescence of optical ceramics under gamma-rays, ions, and 14MeV neutron irradiation. Radiation induced luminescence will be sometimes hazardous for optical diagnostics, but it will be also beneficial as a radiation-dosimetry-sensor. Fused silica (SiC2) emits strong radioluminescence peaks in a visible wavelength range, and behaviors of radioluminescence peaks were found to be strongly modified by existence of oxyhydrate (OH). Alumina (Al2O 3) is another candidate material for optical windows and it usually has a strong radioluminescence peak at about 693nm, which is caused by the impurity chromium. The radioluminescence peak at 693nm of chromium doped alumina (ruby) is well-established peak for application to the radiation dosimetry, but its intensity changed complicated with changes of irradiation doses, irradiation temperatures and energies of incident ions. Some ceramics, such as strontium aluminates showed radioluminescence under the 14MeV neutron irradiation, and they can be used as a sensor for the 14MeV fusion neutrons.