Provided is an energy storage device which can easily fix plates of an electrode assembly to a container. An energy storage device (10) includes: an electrode assembly (500) formed by stacking plates; and a container (100) which accommodates the electrode assembly (500), wherein the container (100) includes: a body portion (200); and a conductive terminal portion (300) connected to the body portion (200), and the terminal portion (300) includes a first portion (310) and a second portion (320) which sandwich the plates therebetween.