A technique of manufacturing a semiconductor device includes forming a film on a substrate in a process chamber by supplying a precursor and a reactant to the substrate under a first temperature at which the precursor and the reactant are not pyrolyzed, and purging, after performing the act of forming the film, an interior of the process chamber by supplying at least one selected from a group consisting of a plasma-excited gas, an alcohol, and a reducing agent into the process chamber under a second temperature equal to or lower than the first temperature.