A final polishing method using a polishing agent that contains colloidal silica, ammonia, and hydroxyethyl cellulose in which the colloidal silica has a primary particle size of 20 nm or more and less than 30 nm, the hydroxyethyl cellulose has a weight average molecular weight of 400,000 to 700,000, and the polishing agent satisfies 1.5≤D1/D2≤2.5 where D1 is a particle size having a cumulative volume percentage of 95% of particles contained in the polishing agent, and D2 is a particle size having a cumulative volume percentage of 95% of the colloidal silica in case of dispersing the colloidal silica in water with a concentration identical to a colloidal silica concentration in the polishing agent, and using a polishing pad that exhibits a contact angle of 60° or more 100 seconds after dropping pure water to the polishing pad that has been subjected to seasoning and then dried.