A method of manufacturing a semiconductor device having a metal oxide film with workpiece accommodated in a chamber, includes: supplying a precursor gas containing a metal complex into the chamber to form a precursor layer on the workpiece from the precursor gas; supplying an oxidizing gas into the chamber to oxidize the precursor layer so that a metal oxide layer is formed, the oxidizing gas being a gas containing H2O or a gas having a functional group containing hydrogen atoms in the metal complex and containing an oxidant to generate H2O by reaction with the functional group; supplying an H2O removal gas containing alcohols or amines into the chamber to remove H2O adsorbed onto the metal oxide layer; and executing a plurality of cycles each including the supplying a precursor gas and the supplying an oxidizing gas. At least some of the cycles includes the supplying an H2O removal gas.