A production method of a semiconductor device including: producing a polishing composition containing zirconium oxide sol; and planarizing a substrate having an uneven surface with said polishing composition, wherein the polishing composition containing zirconium oxide is produced by the steps comprising: baking at a temperature ranging from 400 to 1000.degree. C., a zirconium compound having d50 (where d50 represents a particle diameter meaning that the number of particles having this particle diameter or less is 50% of the total number of particles) of zirconium compound particles of 5 to 25 .mu.m and d99 (where d99 represents a particle diameter meaning that the number of particles having this particle diameter or less is 99% of the total number of particles) of zirconium compound particles of 60 .mu.m or less, wherein d50 and d99 are measured by measuring a slurry of the zirconium compound by a laser diffractometry; and wet-grinding a powder of zirconium oxide obtained in the above baking in an aqueous medium until d50 of zirconium oxide particles becomes 80 to 150 nm and d99 of zirconium oxide particles becomes 150 to 500 nm, wherein d50 and d99 are measured by measuring a slurry of the zirconium compound by a laser diffractometry.