A busbar for connecting a circuit body thereto, comprising: a battery connecting portion for connecting electrodes of two batteries to each other; and a circuit body connecting portion continued to the battery connecting portion, the circuit body connecting portion being configured to be connected directly to a conductive core wire of a circuit body by overlapping the conductive core wire of the circuit body on the circuit body connecting portion, wherein the circuit body connecting portion comprises: a welding portion, at which the conductive core wire of the circuit body can be welded by resistance; and a pair of bridge portions have a plate shape arranged at an interval to each other in parallel to each other and connecting the welding portion as well as the battery connecting portion, wherein the welding portion is formed into a rectangular shape so as to align a lengthwise direction thereof in parallel to the lengthwise direction of the battery connecting portion, wherein a cross-section area of the bridge portions along an intersecting direction intersecting a direction of connecting the welding portion and the battery connecting portion is configured to be smaller than a cross-section area of the welding portion along the intersecting direction, wherein the welding portion comprises a projection formed into a rectangular shape and provided on a surface of the welding portion, the projection being configured such that the conductive core wire of the circuit body can be overlapped on and welded by resistance on the projection. a battery connecting portion for connecting electrodes of two batteries to each other; and a circuit body connecting portion continued to the battery connecting portion, the circuit body connecting portion being configured to be connected directly to a conductive core wire of a circuit body by overlapping the conductive core wire of the circuit body on the circuit body connecting portion, wherein the circuit body connecting portion comprises: a welding portion, at which the conductive core wire of the circuit body can be welded by resistance; and a pair of bridge portions have a plate shape arranged at an interval to each other in parallel to each other and connecting the welding portion as well as the battery connecting portion, wherein the welding portion is formed into a rectangular shape so as to align a lengthwise direction thereof in parallel to the lengthwise direction of the battery connecting portion, wherein a cross-section area of the bridge portions along an intersecting direction intersecting a direction of connecting the welding portion and the battery connecting portion is configured to be smaller than a cross-section area of the welding portion along the intersecting direction, wherein the welding portion comprises a projection formed into a rectangular shape and provided on a surface of the welding portion, the projection being configured such that the conductive core wire of the circuit body can be overlapped on and welded by resistance on the projection. a welding portion, at which the conductive core wire of the circuit body can be welded by resistance; and a pair of bridge portions have a plate shape arranged at an interval to each other in parallel to each other and connecting the welding portion as well as the battery connecting portion, wherein the welding portion is formed into a rectangular shape so as to align a lengthwise direction thereof in parallel to the lengthwise direction of the battery connecting portion, wherein a cross-section area of the bridge portions along an intersecting direction intersecting a direction of connecting the welding portion and the battery connecting portion is configured to be smaller than a cross-section area of the welding portion along the intersecting direction, wherein the welding portion comprises a projection formed into a rectangular shape and provided on a surface of the welding portion, the projection being configured such that the conductive core wire of the circuit body can be overlapped on and welded by resistance on the projection.