Provided are a busbar unit and a method of manufacturing thereof configured to prevent an increase in resistance at a connection portion therebetween, to provide a good connection condition, and to easily achieve even a complicated wiring structure, in the case of connecting between a busbar and a pre-welded member (a terminal, another busbar, or the like) made of a metal material different from that of the busbar. A busbar unit includes a busbar made of a first metal material, and a welded member made of a second metal material to be connected to an end portion of the busbar. A welded portion between the end portion of the busbar and the welded member is configured by pressure welding between end surfaces butted against each other.