A method for manufacturing a silica sol according to an embodiment of the present invention includes: a step of preparing a silica sol reaction liquid by hydrolyzing and polycondensing an alkoxysilane or a condensate thereof using an alkali catalyst in a solvent; and at least one of a step of concentrating the silica sol reaction liquid by an ultrasonic atomization separation method and a step of replacing the silica sol reaction liquid with water by the ultrasonic atomization separation method.