In the cross-section photograph of zirconia sintered body, based on the sectional area of each zirconia particles, the conversion partial size assumed when the cross sectional shape of each zirconia particles is round is calculated, based on the partial size that converts, each zirconia particles are classified as lower than 0.4μm,0.4 μm more than or lower than 0.76 μm and 0.76 μm or more, in each rank, when calculating ratio of the sectional areas at different levels relative to the total sectional area for the total zirconia particles for calculating sectional area, conversion partial size is lower than 0.The section area ratio of 4 μm of zirconia particles is 4% or more and 35% hereinafter, conversion partial size is 0.4 μm more than or lower than 0.The section area ratio of 76 μm of zirconia particles is 24% or more and 57% hereinafter, conversion partial size is 0.The section area ratio of 76 μm or more of zirconia particles is 16% or more and 62% or less.
