There is provided a process of forming a film containing a metal element, an additional element different from the metal element and at least one of nitrogen and carbon on a substrate by performing a cycle a predetermined number of times, the cycle including non-simultaneously performing: (a) supplying a first precursor gas containing the metal element and a second precursor gas containing the additional element to the substrate so that supply periods of the first precursor gas and the second precursor gas at least partially overlap with each other; and (b) supplying a reaction gas containing the at least one of nitrogen and carbon to the substrate.