Abstract: A method of manufacturing a semiconductor device includes forming a thin film on a substrate by performing a cycle a predetermined number of times. The cycle includes supplying a source gas to the substrate, and supplying excited species from each of a plurality of excitation units provided at a side of the substrate to the substrate. Each of the plurality of excitation units generates the excited species by plasma-exciting a reaction gas. In supplying the excited species from each of the plurality of excitation units, an in-plane distribution of the excited species supplied from at least one of the plurality of excitation units in the substrate differs from an in-plane distribution of the excited species supplied from another excitation unit, other than the at least one excitation unit, among the plurality of excitation units, in the substrate.