Abstract: A battery pack 10 includes a housing 11, a group of cells 12, a board 13, a plurality of second terminals 14, and a cover 15. An opening 16c is formed in the housing 11. The board 13 has a terminal arranging part 13A. A plurality of the second terminals 14 are arranged on the terminal arranging part 13A of the board 13. The cover 15 has a plate-like shape, and covers an area of the board 13 which is positioned between the terminal arranging part 13A and the opening 16c.