Abstract: A substrate treatment method includes: developing a substrate which has a coating film of a metal-containing resist formed thereon and has been subjected to an exposure treatment and a heat treatment after the exposure treatment, the developing including: exposing the substrate to an acid atmosphere being an atmosphere containing gas of a weak acid under a pressure of an atmospheric pressure or higher; and removing a product produced by a reaction between the metal-containing resist and the gas of the weak acid, by heating the substrate.

Abstract: A gas treatment method includes: a process (a) of allowing gas to be treated in which a target substance to be treated is mixed with air to pass through inside a housing, the target substance to be treated exhibiting volatility at room temperature and belonging to at least one substance selected from a group consisting of carbon compounds, nitrogen compounds, and sulfur compounds; a process (b) of introducing ozone into a space through which the gas to be treated flows inside the housing at 200° C. or lower; a process (c) of stirring the gas to be treated after the process (b); and a process (d) of heating the gas to be treated to 300° C. or higher after executing the process (c).