BATTERY CASE LID AND MANUFACTURING METHOD FOR BATTERY CASE LID

It is an objective of the present invention to provide a battery case lid and a manufacturing method for the battery case lid which inhibit work hardening of a metal plate workpiece and which facilitate manufacture of a battery case lid. Provided is a battery case lid () formed by working a metal plate, including: a substrate section () and an explosion-proof valve () formed in the substrate section (), wherein the explosion-proof valve () has a reduced thickness section () thinner than the substrate section (), and the reduced thickness section () is formed by extending the metal plate by applying pressure while the metal plate is kept unrestrained.