There is provided a tungsten film forming method which includes: forming a first tungsten film on a substrate; and forming a second tungsten film on the first tungsten film. The forming a first tungsten film includes alternately supplying a first raw material gas containing tungsten and a diborane gas together with a first carrier gas to the substrate. The forming a second tungsten film includes alternately supplying a second raw material gas containing tungsten and a hydrogen gas together with a second carrier gas to the substrate on which the first tungsten film is formed. The first carrier gas is a nitrogen gas. The second carrier gas includes at least one kind of inert gas and has a noble gas at a flow rate of 70% or more with respect to a total flow rate of the second carrier gas.