PURPOSE: To make cutting of lithium plate easy, and make uniform reaction distribution of a lithium electrode after battery assembling to increase discharge utilization by decreasing the thickness of lithium plate to be cut, then cutting it.

CONSTITUTION: A press rod 12 having a ring-shaped pressing part 12a is applied to the position to be cut of a lithium plate 1a placed on a table 11 to reduce its thickness and enlarge the pressed part of the lithium in the inside and outside directions of the diameter of the pressing part 12a. The press rod 12 is drawn up, then the thickness reduced part of lithium plate 1a is cut out with a blanking punch 13. A lithium disc 1b obtained is assembled so that its surface pressed with the press rod 12 is placed to a separator. Thereby, discharge utilization of the lithium is increased compared with a lithium disc having uniform thickness.