A process for producing a separator material suitable for fuel cells, wherein the separator includes a pure titanium or a titanium alloy as a base material. The method comprises an application step and a heat treatment step. The application step is a step of applying a carbon black to a surface of the base material which has a carbon concentration, at a position located at a depth of 10 nm from an outermost surface, of 10 atom % or less. The heat treatment step subjects the base material, which has undergone the application step, to a heat treatment in a low-partial-oxygen-pressure atmosphere having a partial oxygen pressure of 0.0667 Pa or more and 25 Pa or less.