Excellent transparent YAG (Y₃Al₅O₁₂) ceramics containing Ce additives of 0.06 to 3.8mol% and small amount of Si as sintering aids were fabricated by a simple solid-state reaction method using high-purity powders of Y₂O₃, Al₂O₃ and CeO₂. Ce: YAG ceramics, after vacuum sintering at 1750°C for 10h, became fully transparent. Ce: YAG ceramics obtained was confirmed optically perfect isotropy in the dark field image under crossed nicols using a polarizing microscopy. When the electron beam irradiated to Ce: YAG ceramics with perfect optically isotropy and pore-free structure, the fluorescent image for the electron beam became extremely homogeneous and clear.