Matsushita Electric Industrial Co., Ltd.

Ikkoseiko Co., Ltd.

Shigekazu Tanaka

Katsuhiko Mori

Susumu Kitaoka

Shoji Yamashita

A prismatic battery case () has a configuration wherein a rectangular shorter-side plate () has a thickness (A) larger than a thickness (B) of a longer-side plate (). When the prismatic battery case () is manufactured, a battery case material () punched into a predetermined shape undergoes deep drawing to form a first intermediate cup element () having a substantially elliptic cross section; the first intermediate cup element () undergoes redrawing successively in a plural stages to form a second intermediate cup element () having a substantially elliptic cross section which is smaller in minor-axis-diameter to major-axis-diameter ratio; and the second intermediate cup element () undergoes DI processing to form the prismatic battery case () having a substantially rectangular cross section wherein the thickness (A) of the shorter-side plate () is made larger than the thickness (B) of the longer-side plate ().

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Higashiosaka, Japan

Shigekazu Tanaka