Provided is a technique including forming a film by performing a cycle a predetermined number of times. The cycle includes: forming a first layer by supplying a gas containing a first element under a condition where chemical adsorption of a molecule constituting the gas containing the first element is not saturated; forming a second layer including the first layer and a layer including a second element stacked on the first layer by supplying a gas containing the second element under a condition where chemical adsorption of a molecule constituting the gas containing the second element is not saturated; and forming a third layer by supplying a gas containing a third element to modify the second layer under a condition where a modifying reaction of the second layer by the gas containing the third element is not saturated.