A method for forming a silicon film includes supplying a first processing gas including a silicon-containing gas to a substrate to deposit a first silicon film under a first processing condition; and supplying a second processing gas including the silicon-containing gas to the substrate to deposit a second silicon film under a second processing condition. A second in-plane distribution of film characteristic when the second silicon film is deposited under the second processing condition is different from a first in-plane distribution of the film characteristic when the first silicon film is deposited under the first processing condition.