A busbar module (5) includes a case (6) that is assembled to a battery module (2), and a flexible substrate (7) that is held in the case (6). A main body (71) of the flexible substrate (7) includes a trunk portion (711), and a branch portion (712) branched from the trunk portion (711). Meanwhile, the case (6) includes a trunk holding portion (61), a branch holding portion (62) that is positioned closer to the battery module (2) side than the trunk holding portion (61), and a connecting wall (63) that connects the trunk holding portion (61) and the branch holding portion (62). The trunk holding portion (61), the branch holding portion (62), and the connecting wall (63) form a stepped portion. Further, the branch portion (712) includes a curved portion (7122) that curves smoothly in a connecting portion with the trunk portion (711). A holding portion (64) that holds the main body (71) in a state in which a curved shape of the curved portion (7122) is maintained is formed in the case (6).
