An alumina sintered body of the present invention has a degree of c-plane orientation of 5% or more, which is determined by a Lotgering method using an X-ray diffraction profile in a range of 2θ=20° to 70° obtained under X-ray irradiation, and an XRC half width of 15.0° or less in rocking curve measurement, an F content of less than 0.99 mass ppm when measured by D-SIMS, a crystal grain diameter of 15 to 200 μm, and 25 or less pores having a diameter of 0.2 μm to 1.0 μm when a photograph of a viewing area 370.0 μm in a vertical direction and 372.0 μm in a horizontal direction taken at a magnification factor of 1000 is visually observed.