The present invention is to provide a display for a secondary battery in response to the status thereof. For this end, the secondary battery is provided with the display section including LEDs and the switch. If the switch is operated while the secondary battery is being exhibited in a shop, displays to give an image what happens after purchase of the secondary battery are preformed in the display section. Such displays differ from each other in the charging mode and the discharging mode of the secondary battery. For example, in the charging mode, LEDs are sequentially lighted to indicate that the secondary battery is being charged. Additionally, by controlling the LEDs based on the timing calculated from the charging current magnitude through the secondary battery, it is possible to indicate such information if the charging is approaching to the final stage.