Energy Storage Device

The present invention provides an energy storage device which can maintain energy storage performance for a long period by suppressing loosening of connection between a terminal or a current collector and a conductive member. An energy storage device includes: a container; a terminal disposed outside the container or a current collector disposed inside the container; a conductive member penetrating the container and connected to the current collector or the terminal; and a fixing member joining the current collector or the terminal and the conductive member to each other. 本发明提供种蓄电元件，能够通过抑制导电部件的松弛来长期维持蓄电性能。蓄电元件(10)具备：容器(100)、配置于容器(100)的外侧的端子(正极端子200)或者配置于容器(100)的内侧的集电体(正极集电体120)、贯通容器(100)且与集电体或者端子连接的导电部件(300)、以及对集电体与导电部件(300)或者端子与导电部件(300)进行接合的固定部件(第固定部件600、第二固定部件800)。