To provide a method for continuously annealing a steel sheet, which inhibits discoloration in a cooling zone even if a treatment condition for the steel sheet varies, and to provide a facility therefor.

The method for continuously annealing the steel sheet is characterized by making an atmosphere in which temperatures of the steel sheet while being cooled are 700°C or higher, to be an oxygen-containing atmosphere, when continuously heat-treating the steel sheet and cooling it while passing it. The apparatus for continuously annealing the steel sheet comprises a means for supplying oxygen and/or air to the front stage of the cooling zone, a means for measuring oxygen concentration in the atmosphere of the above front stage of the cooling zone, and a means for adjusting amounts of the above oxygen and/or air supply so that the above measured concentration of oxygen can be a desired value.