A spin base is caused to rotate at a number of revolutions of from 250 rmp to 350 rpm (first number of revolutions), and at the same time, a cleaning solution is supplied to a holding surface of a spin base while the upper end of a processing cup is placed below the holding surface. Thus, an outer upper surface of the processing cup is cleaned with the cleaning solution scattered from the holding surface. Then, the spin base is caused to rotate at a number of revolutions of from 350 rpm to 450 rpm (second number of revolutions) higher than the first number of revolutions, and at the same time, a cleaning solution is supplied onto the holding surface. Thus, a partition plate outside the processing cup is cleaned with the cleaning solution scattered from the rotating holding surface.