CONNECTION MODULE

Provided is a technique that prevents impairment of attachability of an external connection bus bar. The present specification discloses a connection module to be attached to a power storage element group constituted by a plurality of power storage elements each having positive and negative electrode terminals and arranged side by side, the connection module including: a negative-electrode external connection bus bar that includes a plate-shaped extension portion and is configured to be electrically connected to an electrode terminal; and a second protector that holds the negative-electrode external connection bus bar. The second protector includes a placement portion on which the extension portion is placed and a locking portion that has a locking surface facing the placement portion, and the extension portion is provided with an extended locking piece that extends from the extension portion toward the locking surface.