本发明的氧化铝烧结体的特征在于，当X射线照射板表面时，利用2θ= 20〜70度的X射线衍射曲线通过Lotgering法得到的c面取向度为90 ％，使用Ar离子束和遮蔽板对与板面垂直的方向切断的截面进行研磨，用5000倍的扫描型电子显微镜照射孔隙数为0个，除Mg，C以外的杂质元素 总质量比为100ppm或更少。 由于该氧化铝烧结体具有高取向性，高密度和高纯度，因此其具有比传统高的透光率。

Alumina sintered body of the present invention, a c-plane orientation degree determined according to the 2θ = 20 ° ~70 ° (Lotgering method) to the lot by using the X-ray diffraction profile ringbeop in the range was irradiated using an X-ray with respect to the printing plate not less than 90%, and the number of pores zero at the time the printing plate and after the cutting section in the direction perpendicular to the grinding using Ar ⁺ ion beam and a shielding plate with a scanning electron microscope was irradiated fold magnification 5000, other than Mg, C the ratio of the total mass of the impurity element is not more than 100 ppm. Since the alumina sintered body, the highly-oriented, high density, high purity, has a high light transmission in comparison with the prior art.