A method of producing a composite material which includes a carbon-based material and a particulate or fibrous metal material Z. The method includes steps (a) to (c). In the step (a), at least a first carbon material and the metal material Z mixed into an elastomer, and dispersing the first carbon material and the metal material Z by applying a shear force to obtain a composite elastomer, the metal material Z having a melting point lower than a melting point of the first carbon material. In the step (b), the composite elastomer is heat-treated to vaporize the elastomer to obtain an intermediate composite material including a second carbon material and the metal material Z. In the step (c), the intermediate composite material is heat-treated together with a substance including an element Y having a melting point lower than the melting point of the metal material Z to vaporize the substance including the element Y.