PURPOSE: To continuously manufacture a header tank where the waste of the stock is eliminated, and the changing works of a die is reduced by feeding the stock in the longitudinal direction at the prescribed pitch, successively forming a tube inserting in this fed stock, and successively bend the plate-shaped stock to be fed.

CONSTITUTION: A press 18 is provided with a lower plate 19 and an upper plate 20 which are arranged opposite to each other, and also provided with a driving device to press a lower plate 10 and an upper plate 20 so as to be opposite to each other. A lower die 21 of a press die 17 is fixed to the lower plate 19, and an upper die 22 is fixed to the upper plate 20, and a brazing sheet 4A which is a stock is fed between the lower die 21 and the upper die 22, and the brazing sheet is fed at the prescribed feeding pitch, the lower plate 19 and the upper plate 20 are pressed against each other to execute the press forming. A heater tank 4 continuous from the front side of the press 18 can be obtained by repeating the feeding of the brazing sheet 4A and the press.