To provide a silicon-based composite material into which carbon nanofibers are uniformly dispersed, and its production method.

The method of producing the silicon-based composite material is characterized by comprising a process (a) for mixing an elastomer 30 with a carbon nanofiber 40 and dispersing by shearing force to obtain a composite elastomer, a process (b) for decomposing and vaporizing the elastomer 30 contained in the composite elastomer by its heat treatment to obtain a carbon-based material, and a process (c-1) for impregnating the carbon-based material with the melt of a matrix material whose main component is silicon.