In a method of polishing a silicon wafer, a final polishing step includes an upstream polishing step and a subsequent finish polishing step. In the upstream polishing step, as a polishing agent, a first alkaline aqueous solution containing abrasive grains with a density of 1×1014/cm3 or more is first supplied, and the supply is then switched to a supply of a second alkaline aqueous solution containing a water-soluble polymer and abrasive grains with a density of 5×1013/cm3 or less. In the finish polishing step, as a polishing agent, a third alkaline aqueous solution containing a water-soluble polymer and abrasive grains with a density of 5×10′13/cm3 or less is supplied. Thus, the formation of not only PIDs but also scratches with small depth can be suppressed.