In the cross-sectional photograph of the zirconia sintered body, based on the cross-sectional area of each zirconia particle, the converted particle diameter when the cross-sectional shape of each zirconia particle is assumed to be circular is calculated, and each zirconia is calculated based on the converted particle diameter. Particles are classified into less than 0.4 μm, 0.4 μm or more and less than 0.76 μm and 0.76 μm or more, and in each class, the cross-sectional area ratio of each class to the total cross-sectional area of all zirconia particles for which the cross-sectional area is calculated is calculated. The cross-sectional area ratio of zirconia particles having a converted particle diameter of less than 0.4 μm is 4% or more and 35% or less, and the cross-sectional area ratio of zirconia particles having a converted particle diameter of 0.4 μm or more and less than 0.76 μm is 24%. The cross-sectional area ratio of zirconia particles having a converted particle size of 0.76 μm or more is 16% or more and 62% or less.ジルコニア焼結体の断面写真において、各ジルコニア粒子の断面積を基に、各ジルコニア粒子の断面形状が円形であると仮定した場合の換算粒径を算出し、換算粒径を基に、各ジルコニア粒子を０．４μｍ未満、０．４μｍ以上０．７６μｍ未満及び０．７６μｍ以上にクラス分けし、各クラスにおいて、断面積を算出した全ジルコニア粒子の総断面積に対する各クラスの断面積割合を算出した場合、換算粒径が０．４μｍ未満のジルコニア粒子の断面積割合が４％以上３５％以下であり、換算粒径が０．４μｍ以上０．７６μｍ未満のジルコニア粒子の断面積割合が２４％以上５７％以下であり、換算粒径が０．７６μｍ以上のジルコニア粒子の断面積割合が１６％以上６２％以下である。
