Assembly of a circuit body, a battery assembly and a connector wherein the circuit body is attached to the battery assembly in which electrodes of a plurality of battery cells are arranged in two rows and two or more electrodes adjacent to each other in each row are connected by a conductive member (20A, 20B), comprising: a plurality of conductors and a substrate (31, 32, 31A, 32A) having flexibility and provided with the plurality of conductors, wherein the substrate (31, 32, 31A, 32A) includes a battery wiring portion (31a, 32a) which is routed along each row of the electrodes and where one ends of the plurality of conductors are respectively connected to the conductive members (20A, 20B), and a pair of connector connecting portions (31c, 32c) in which the other ends of the conductors provided in respective battery wiring portions (31a, 32a) are respectively located, the pair of connector connecting portions (31c, 32c) include a connector mounting portion which is a position where the connector connecting portions (31c, 32c) are guided from opposite directions and connected and where the connector is mounted, in the connector mounting portion, the other ends of the conductors of the pair of the connector connecting portions (31c, 32c) are alternately arranged and an arrangement order corresponds to the potential order of the conductive members (20A, 20B) connected to the conductors, wherein the substrate (31A, 32A) is formed of two sheets, and the connector mounting portion is located at a position where the connector connecting portions (31c, 32c) of the two substrates (31A, 32A) are connected in an opposite direction to each other, characterized in that the connector connecting portions (31c, 32c) of the two substrates (31A, 32A) are overlapped in the connector mounting portion, and a through hole for connecting the conductor of the substrate on a far side with respect to the connector and a terminal of the connector is formed in the substrate on a near side with respect to the connector. a plurality of conductors and a substrate (31, 32, 31A, 32A) having flexibility and provided with the plurality of conductors, wherein the substrate (31, 32, 31A, 32A) includes a battery wiring portion (31a, 32a) which is routed along each row of the electrodes and where one ends of the plurality of conductors are respectively connected to the conductive members (20A, 20B), and a pair of connector connecting portions (31c, 32c) in which the other ends of the conductors provided in respective battery wiring portions (31a, 32a) are respectively located, the pair of connector connecting portions (31c, 32c) include a connector mounting portion which is a position where the connector connecting portions (31c, 32c) are guided from opposite directions and connected and where the connector is mounted, in the connector mounting portion, the other ends of the conductors of the pair of the connector connecting portions (31c, 32c) are alternately arranged and an arrangement order corresponds to the potential order of the conductive members (20A, 20B) connected to the conductors, wherein the substrate (31A, 32A) is formed of two sheets, and the connector mounting portion is located at a position where the connector connecting portions (31c, 32c) of the two substrates (31A, 32A) are connected in an opposite direction to each other, characterized in that the connector connecting portions (31c, 32c) of the two substrates (31A, 32A) are overlapped in the connector mounting portion, and a through hole for connecting the conductor of the substrate on a far side with respect to the connector and a terminal of the connector is formed in the substrate on a near side with respect to the connector.