Substrate processing apparatus and nozzle cleaning method

The controller of a substrate processing apparatus carries out a liquid column forming step in which cleaning liquid is discharged through a lower surface nozzle when a spin chuck is not holding a substrate, to form a liquid column extending upward from the lower surface nozzle, and, in parallel with the liquid column forming step, a first dropping portion cleaning step in which an upper surface nozzle is reciprocated horizontally between a first position where a dropping portion of the upper surface nozzle does not contact the liquid column and a second position where the dropping portion of the upper surface nozzle does not contact the liquid column, so as to cause the upper surface nozzle to pass through a first middle position where the upper discharge port of the upper surface nozzle overlaps with the liquid column in a plan view.