Disclosed is a patterning method including: forming a first film on a substrate; forming a first resist film on the first film; processing the first resist film into a first resist pattern having a preset pitch by photolithography; forming a silicon oxide film on the first resist pattern and the first film by alternately supplying a first gas containing organic silicon and a second gas containing an activated oxygen species to the substrate; forming a second resist film on the silicon oxide film; processing the second resist film into a second resist pattern having a preset pitch by the photolithography; and processing the first film by using the first resist pattern and the second resist pattern as a mask.