A sintered zirconia material containing at least 50 mol % tetragonal zirconia and 1.5-5 mol % yttria, from which carbon is substantially absent, the porosity of which is not greater than 0.6%, the pore size of which is not greater than 0.1 .mu.m and the pores of which exist mainly at triple points of zirconia grain boundaries. The sintered zirconia material can be obtained by sintering the raw material zirconia powder, the green body or the presintered material containing tetragonal zirconia and yttria in a required amount and in an oxidizing atmosphere, by hot isostatic pressing.The sintered material thus obtained has a high strength and high toughness, and particularly excellent properties for use under conditions of higher than 600.degree. C. and can be used as a material of various industrial machines or tools.