PROBLEM TO BE SOLVED: To provide a zirconia sintered compact combining high translucency with high strength.SOLUTION: The zirconia sintered compact is provided which includes a crystal particle having a cubic crystal domain and a tetragonal crystal domain, a stabilizer and lanthanum each in a solid-solved form and has an average crystalline diameter of over 255 nm calculated from half width value of peak at 2θ=30±2° in a powder X ray diffraction pattern with CuKα as a radiation source. A production method for zirconia sintered compact is also provided that includes a mixing step of mixing a zirconia raw material, a stabilizer raw material and a lanthanum raw material including lanthanum hydroxide of 0.1 to 10 mol% to obtain a mixed powder, a molding step of molding the resulting mixed powder to obtain a molding, a sintering step of sintering the resulting molding at a sintering temperature of 1650°C or more to obtain a sintered compact and a temperature decreasing step of decreasing a temperature from the sintering temperature to 1000°C at a decreasing temperature of over 1°C/min, the average particle diameter of the lanthanum raw material in the mixed powder being larger than average particle diameter of the zirconia raw material.SELECTED DRAWING: Figure 4【課題】高い透光性及び高い強度を兼備したジルコニア焼結体の提供。【解決手段】立方晶ドメイン及び正方晶ドメインを有する結晶粒子を含み、安定化剤及びランタンを固溶し、なおかつ、ＣｕＫαを線源とする粉末Ｘ線回折パターンにおける２θ＝３０±２°のピークの半値幅から算出される平均結晶子径が２５５ｎｍ超であるジルコニア焼結体。ジルコニア原料、安定化剤原料、及び、水酸化ランタンを含むランタン原料０．１～１０ｍｏｌ％を混合して混合粉末を得る混合工程、得られた混合粉末を成形して成形体を得る成形工程、得られた成形体を１６５０℃以上の焼結温度で焼結して焼結体を得る焼結工程、及び、焼結温度から１０００℃までを１℃／ｍｉｎ超の降温速度で降温する降温工程、を含み、なおかつ、前記混合粉末におけるランタン原料の平均粒子径がジルコニア原料の平均粒子径よりも大きい製造方法。【選択図】図４
