An apparatus for continuous treatment of cold rolled steel sheet. The apparatus has a continuous annealing furnace through which the sheet is continuously passed and which is composed of, in succession, a heating chamber for heating the cold rolled steel sheet to a temperature range of 700.degree. to 900.degree. C. within 2 minutes, a soaking chamber for keeping the sheet in the above temperature range for two minutes or less, a primary cooling chamber for rapidly cooling the sheet from the above temperature range to an overageing at a rate of 5.degree. to 30.degree. C./sec., an overageing chamber for keeping the sheet between 300.degree. to 400.degree. C. for up to eight minutes, and a secondary cooling chamber for cooling the sheet from the above overageing temperature to below 50.degree. C. within 2 minutes. Adjacent the output end of said furnace is apparatus for successively skin pass rolling, levelling and recoiling the sheet from the annealing furnace. The skin pass rolling apparatus has apparatus for replacing the working rolls.