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.

Abstract: Colloidal silica containing silica particles that have a small particle size (e.g., an average primary particle size of 20 nm or less) and that contain alkoxy groups, and a method for producing the colloidal silica, are disclosed. The colloidal silica containing silica particles can have a small particle size and exhibit a suppressed increase in the average secondary particle size after storage. The colloidal silica containing silica particles wherein the silica particles have an average primary particle size of 20 nm or less, the silica particles have a ratio (m/n) of the content of alkoxy groups m (ppm) to the average primary particle size n (nm) of 300 or more, the silica particles have a particle density of 1.95 or more, and the silica particles have an increase rate of average secondary particle size of 12% or less in a storage stability test.