To reduce variation in the life of a battery caused by individual differences among batteries or equipment such as a camera using a battery, by stabilizing a contact resistance between the battery and a terminal to be a lower value.

To enhance a self-cleaning effect by increasing friction force between a contact part of the battery connection terminal and an electrode of the battery, the contact of the battery connection terminal is formed to be rough. As a method for forming the contact of the terminal to be rough, a material 40 to be a terminal plate is etched for a long time. When stainless steel is used as the material 40 and a mixture of fluorine and nitric acid is used as an etching solvent, the etching time before plating is generally one to two minutes. However, to make the surface rough, the etching time is set to be longer than the time in a regular case. Then, a nickel layer 42 is formed on the surface by nickel plating, and then, a nickel boron layer 44 is formed on the nickel layer 42 by nickel boron plating.