Silica sol having particle size distribution and production method therefor

A silica sol comprising silica particles exhibiting an average particle diameter distribution having at least two peaks, and a basic substance, characterized in that:

• the at least two peaks include a peak a which is largest in a range of D50 to D90 and is present in a range of 35 nm or more and 115 nm or less, and a peak b which is largest in a range of D10 to D50 and is present in a range of 5 nm or more and less than 35 nm;
• the silica particles contain, in the surfaces of at least a portion thereof, an organic group directly bonded to a silicon atom via an Si—C bond and an alkoxy group consisting of a methoxy group or an ethoxy group;
• and the alkoxy group is bonded to the surfaces of the silica particles in an amount of 0.6 to 3.0/nm2, and
• wherein peak a is higher than peak b.