A bus bar module has a bus bar housing portion housing a plurality of bus bars placed side by side in a first direction, and a plurality of voltage detecting lines extending in the first direction and each connected electrically to a different one of the bus bars through a conductive member. The plurality of voltage detecting lines are placed adjacently to the bus bar housing portion and are placed diagonally in a second direction inclined relative to an in-plane direction including the bus bar such that a first region in the plurality of voltage detecting lines separate from the bus bar housing portion is located below a second region in the plurality of voltage detecting lines closer to the bus bar housing portion.