TECHNOLOGY FOCUS - ELECTRONICS - Preferred Module: The battery module further comprises a circuit board that includes first and second conductor traces that are electrically connected to the voltage detector, where the connecting member is a metal plate arranged to connect electrodes of adjacent battery cells to each other, the metal plate has the first and second regions, and the first and second regions of the metal plate are joined to the first and second conductor traces of the circuit board, respectively. The circuit board includes a flexible member, and the first and second conductor traces are provided on the flexible member. The circuit board further includes first and second conductive plates which are provided on the flexible member so as to be separated from each other and to which the first and second conductor traces are connected, respectively, the metal plate includes a first attachment portion including the first region and a second attachment portion including the second region, and the first and second conductive plates of the circuit board are attached to the first and second attachment portions, respectively. The set of battery cells include at least three battery cells, the connecting member includes a set of metal plates, each of which connects electrodes of adjacent battery cells to each other such that the at least three battery cells are connected in series, the first and second regions are provided in at least one of the set of metal plates, and the voltage detector detects voltages of the set of battery cells by detecting voltages among the set of metal plates and detects the voltage between the first and second regions. The battery module as well comprises an amplifying circuit arranged to amplify the voltage between the first and second regions, where the voltage detector includes a set of input terminals arranged to receive voltages of the set of connecting members or an output voltage of the amplifying circuit, and includes a reference terminal held at a reference voltage of the voltage detector, and the first region is connected to the reference terminal; a storage arranged to store a resistance value between the first region and the second region of the connecting member; a current calculator arranged to calculate a current flowing between the first region and the second region based on the voltage detected by the voltage detector and the resistance value stored in the storage; and a temperature detector arranged to detect a temperature of the set of battery cells, where the current calculator corrects the resistance value stored in the storage based on the temperature detected by the temperature detector.