PURPOSE: To form easily a neck part of a deformed DI can by executing neck- in forming and flanging working while a can drum is cylindrical, and thereafter, executing expanding working, when executing the expanding working to the deformed DI can.

CONSTITUTION: When forming a neck part of a deformed DI can, first of all, while a can drum is cylindrical, neck-in forming and flanging working are executed, and subsequently, expanding working is executed, and as a result, the strength in the cylindrical direction of the can becomes lower than the neck-in forming force by the expanding working, it is not feared that buckling occurs, and the neck part of the deformed DI can can be formed easily.