To provide a substrate processing method that allows particles on a patterned substrate to be removed without the pattern formed on the damaged pattern.

It is possible to remove particles on the substrate by discharging a mist on the patterned substrate by use of a two-fluid nozzle that mixes a pressured gas and a medical fluid to thereby form a mist. The substrate processing is performed by changing a gas flow rate depending on an aspect ratio of the pattern on the substrate. As a preferred processing condition of cleaning a substrate that is formed with an Al wiring pattern, a gas flow rate of 80 L/min is used to process a substrate that is formed with a pattern having an aspect ratio of less than 2.2. A gas flow rate of 60 L/min is used to process a substrate formed with a pattern having an aspect ratio of 2.2 or higher.