There is provided an acidic zirconia sol having compatibility of particle properties and binding properties, and a production method of the same.The present invention relates to a production method of an acidic zirconia sol containing zirconia particles having a particle diameter of less than 20 nm in a content of 10 to 50% by mass, based on the mass of all zirconia particles including: a first process in which an alkaline zirconia sol (A) and a zirconium salt (B) are mixed in a mass ratio (Bs/As) ranging from 0.2 to 5.0 of a mass of a solid content (Bs) which is converted into an amount of ZrO.sub.2 in the zirconium salt (B) to a mass of a solid content (As) which is converted into an amount of ZrO.sub.2 in the alkaline zirconia sol (A); and a second process in which the resultant mixture is reacted at 80 to 250.degree. C. to produce an acidic zirconia sol.