The subject of the present invention relates to obtaining a zirconia sintered body having excellent in both properties of a translucency and a mechanical strength. The present invention relates to obtaining a high-strength zirconia sintered body having a translucency of an in-line transmission of 50% or more at a sample thickness of 1 mm for visible light at a wavelength of 600 nm and an average flexural strength of 300 MPa or more by subjecting a zirconia primary sintered body having an average grain size of 1 μm or less and a relative density of 92% or more and the crystal phase composed of cubic crystals only to HIP treatment at a temperature of 1,250° C. to 1,600° C. and a pressure of at least 50 MPa. The primary sintered body is obtained by maintaining a molded body of a zirconia powder containing 7 mol % to 30 mol % of yttria at 1,100° C. to 1,300° C. for at least 5 hrs or by heating the molded body at a high rate of temperature rise of 500° C./hr or more.