A surface treatment method of a fuel cell separator capable of suppressing temperature unevenness of the fuel cell separator is provided. In the surface treatment method, an antimony-doped tin oxide (ATO) film is formed on a surface of a fuel cell separator (W1) used for a fuel cell. The fuel cell separator (W1) is heated using a high-frequency induction heating method (S1). By spraying solution (L1) including antimony and tin onto the fuel cell separator (W1), the ATO film is caused to be formed on the surface of the fuel cell separator (W1) (S2).