A substrate processing technique including: (a) modifying a first base surface of a substrate by supplying a first modifier and a second modifier to the substrate having a surface on which the first base and a second base are exposed, wherein the first modifier contains one or more atoms to which at least one first functional group and at least one second functional group are directly bonded, wherein the second modifier contains an atom to which at least one first functional group and at least one second functional group are directly bonded, and wherein the number of the at least one first functional group contained in one molecule of the second modifier is smaller than the number of the at least one first functional group contained in one molecule of the first modifier; and (b) forming a film on a second base surface by supplying film-forming gas to the substrate.