CONNECTION STRUCTURE BETWEEN FLEXIBLE SUBSTRATE AND BUS BAR, WIRING MODULE AND ELECTRICITY STORAGE MODULE

A connection structure between a flexible substrate and a bus bar includes: a flexible substrate; a plurality of bus bars; and a connection piece, in which the flexible substrate is formed by being covered by a plurality of conductive paths containing a first metal, and a resin base material, the bus bars are formed so as to contain a second metal, the conductive paths include a second conductive path extending from a first conductive path, the resin base material includes a sub-film portion that is branched from a main film portion and extends over the bus bars, the second conductive path is disposed on the sub-film portion, the connection piece is formed so as to contain a third metal that has a higher joining strength of welding to the first metal and the second metal than a joining strength of welding between the first metal and the second metal.