A film where a first layer and a second layer are laminated is formed on a substrate by performing: forming the first layer by performing a first cycle a predetermined number of times, the first cycle including non-simultaneously performing: supplying a source to the substrate, and supplying a reactant to the substrate, under a first temperature at which neither the source nor the reactant is thermally decomposed when the source and the reactant are present alone, respectively; and forming the second layer by performing a second cycle a predetermined number of times, the second cycle including non-simultaneously performing: supplying the source to the substrate, and supplying the reactant to the substrate, under a second temperature at which neither the source nor the reactant is thermally decomposed when the source and the reactant are present alone, respectively, the second temperature being different from the first temperature.