We have succeeded for the first time in synthesizing an optical grade ${({\mathrm{Tb}}_X{\mathrm{Y}}_{1-X})}_2{\mathrm{O}}_3$ ($X=0.5–1.0$) ceramic Faraday rotator, which greatly exceeds the basic characteristics of the commercial terbium gallium garnet (TGG) (${\mathrm{Tb}}_3{\mathrm{Ga}}_5{\mathrm{O}}_{12}$) crystal. The Faraday rotation angle increased as the Tb concentration increased, and the Verdet constant increased from 2.1 ($82\mathrm{rad}{\mathrm{T}}^{-1}{\mathrm{m}}^{-1}$ at $X=0.5$) to 3.8 times ($154\mathrm{rad}{\mathrm{T}}^{-1}{\mathrm{m}}^{-1}$ at $X=1.0$) than the TGG single crystal, which is regarded as highest class. Therefore, it is possible to minimize the Faraday rotator length and the magnet in building an optical isolator. It was also confirmed that its optical quality was very comparable to the commercial TGG crystal.