A processing method of a semiconductor substrate according the present invention includes: cleaning a surface of the semiconductor substrate with a water-based cleaning liquid; and drying the semiconductor substrate by replacing the water-based cleaning liquid attached to the surface of the semiconductor substrate with a supercritical fluid, characterized by using as the supercritical fluid a C.sub.2-C.sub.6 fluoroalcohol-containing solvent whose Fe, Ni, Cr, Al, Zn, Cu, Mg, Li, K, Na and Ca contents are each 500 mass ppb or less. In this processing method, it is possible to reduce the amount of fluorine atoms released in the supercritical fluid.