There is provided a method of forming a film with improved step coverage on a substrate by performing, a predetermined number of times, forming a first layer by supplying a halogen-free precursor having a first chemical bond cut by thermal energy at a first temperature and a second chemical bond cut by thermal energy at a second temperature lower than the first temperature and having a ratio of the number of first chemical bonds to the number of second chemical bonds in one molecule thereof, the ratio being equal to or more than 3, to the substrate at a temperature equal to or higher than the second temperature and lower than the first temperature.