Ammonia gas was blown into the solution of zirconium ion to induce homogeneous precipitation of supersaturated zirconium ion at gas-liquid interface with increase in pH. The precipitates formed using interface of gas-liquid phase were decomposed into fine spherical zirconia powder of high purity. As Concentration increase, mean diameter of particles increases to 140, 180, 240, 290 and 630nm. At pH of 4.5, maximum yield of 98.7% was obtained. From the above pH of 4.5, yield has been kept constant. Above pH of 5.0, large aggregates of precipitate consisting of primary particles were formed, and this may have been caused due to the existence of isoelectric point. Below pH of 4.5, almost aggregate-free fine spherical powders with particle size of below 100nm were produced.