A method for cleaning a semiconductor silicon wafer including: an ozone water treatment step after polishing in ozone water, a step of performing a first ultrasonic-wave-ozone-water treatment of cleaning at room temperature while immersing in ozone water and applying ultrasonic waves; and a step of performing a second ultrasonic-wave-ozone-water treatment of, after the step of performing the first ultrasonic-wave-ozone-water treatment, pulling out the semiconductor silicon wafer from the ozone water, performing rotation process, and cleaning at room temperature while immersing in ozone water and applying ultrasonic waves; wherein the step of performing the second ultrasonic-wave-ozone-water treatment is performed, and a hydrofluoric acid treatment step and an ozone water treatment step are performed. Accordingly, a method for cleaning a semiconductor silicon wafer and an apparatus for cleaning by which projecting defects on the wafer surface and the degradation of surface roughness can be suppressed to improve wafer quality reduce costs.