Provided is a technique of forming a film on a substrate by performing a cycle a predetermined number of times. The cycle includes: forming a first layer by supplying a gas containing a first element to the substrate, wherein the first layer is a discontinuous layer, a continuous layer, or a layer in which at least one of the discontinuous layer or the continuous layer is overlapped; forming a second layer by supplying a gas containing a second element to the substrate to modify the first layer under a condition where a modifying reaction of the first layer by the gas containing the second element is not saturated; and forming a third layer by supplying a gas containing a third element to the substrate 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.