Abstract: The present invention provides colloidal silica that exhibits excellent abrasiveness and contains, with high purity, deformed silica particles with excellent compactness and a large amount of alkoxy groups per unit area; the invention also provides a method for producing the colloidal silica in a simple manner with reduced costs. The invention provides colloidal silica containing silica particles having a bent structure and/or a branched structure, wherein the silica particles have a particle density of 1.95 or more, the silica particles have a ratio (m/n) of the content of alkoxy groups m (ppa) to the average primary particle size n (nm) of 200 or more, and the silica particles having a bent structure and/or a branched structure are present in an amount of 15% or more based on the number of particles in a given field of view as observed with a scanning electron microscope at 200,000-times magnification.

Abstract: The present invention provides colloidal silica containing silica particles excellent in compactness and excellent in maintenance of the bumpy surface under basic conditions, and provides a method for producing the colloidal silica. The present invention provides colloidal silica containing silica particles having a bumpy surface, wherein (1) the silica particles have a content of alkoxy groups of 1000 ppm or more, and (2) the silica particles have a reduction in specific surface area of 15.0% or less when the silica particles are heated under basic conditions.