Disclosed are a black surface-treated steel sheet, which comprises a steel sheet or plated steel sheet and a electrodeposited composite plating coating formed in a deposition amount of 0.1 to 5 g/m.sup.2 on the surface of the steel sheet or plated steel sheet, the plating coating containing metalic Zinc or Zn-Ni alloy and oxides or hydrous oxides and sulfur compound, and a process for the preparation of a black surface-treated steel sheet, which comprises carrying out the electrolysis in an acidic aqueous solution containing Zn.sup.2+ and, as the main components, at least one member selected from the group consisting of Fe.sup.2+, Co.sup.2+ and Ni.sup.2+, an oxidative ion, and a thio compound, by electrolysis a steel sheet or plated steel sheet as the cathode, and water-washing and drying the treated steel sheet.