Abstract: The board assembly portion includes a circuit board, a communication terminal, and an insulating formed section. A data-processing circuit is mounted on the circuit board. The insulating formed section positions the communication terminal in a predetermined position. A penetrating opening is formed in the central part of the board assembly portion to receive the protruding terminal of the base battery portion. The communication terminal that is formed in a ring shape is secured around the periphery of the penetrating opening on the upper surface side of the board assembly portion. The protruding terminal of the base battery portion has a height that protrudes from the upper surface of the board assembly portion. In the state where the board assembly portion is secured to the base battery portion, the whole cylindrical battery has the same exterior size as a standard size battery.