A bus bar module for electrically connecting in series a plurality of batteries stacked against each other in a row with alternately opposite polarities, comprising: a plurality of bus-bars; a housing part including a plurality of housing units for housing each of the plurality of the bus-bars such that the bus bars are movable along three axes, a plurality of voltage detecting terminals for detecting a voltage in each of the plurality of the batteries, and mounted on each of the plurality of the bus-bars; and a flexible cable electrically connected to the plurality of the voltage detecting terminals, wherein each of the plurality of the bus-bars connects together electrodes of two adjacent batteries among the plurality of the batteries, while being provided with two holes (221, 222) for loosely inserting the electrodes, each of the plurality of housing units has a retaining part for retaining each of the plurality of the bus-bars inside each of the plurality of the housing units, characterized in that the retaining part retains each of the plurality of the voltage detecting terminals in each of the plurality of housing units, a cut-away portion (223, 224) is provided at each of the plurality of the bus-bars, each of the plurality of the voltage detecting terminals has a bending portion (232, 233) inserted into the cut-away portion (223, 224), and when each of the plurality of the voltage detecting terminals moves in the direction in which the plurality of the batteries are stacked, the bending portion (232, 233) contacts the cut-away portion (223, 224) of each of the plurality of the bus-bars, and restricts movement of each of the plurality of the voltage detecting terminals. a plurality of bus-bars; a housing part including a plurality of housing units for housing each of the plurality of the bus-bars such that the bus bars are movable along three axes, a plurality of voltage detecting terminals for detecting a voltage in each of the plurality of the batteries, and mounted on each of the plurality of the bus-bars; and a flexible cable electrically connected to the plurality of the voltage detecting terminals, wherein each of the plurality of the bus-bars connects together electrodes of two adjacent batteries among the plurality of the batteries, while being provided with two holes (221, 222) for loosely inserting the electrodes, each of the plurality of housing units has a retaining part for retaining each of the plurality of the bus-bars inside each of the plurality of the housing units, characterized in that the retaining part retains each of the plurality of the voltage detecting terminals in each of the plurality of housing units, a cut-away portion (223, 224) is provided at each of the plurality of the bus-bars, each of the plurality of the voltage detecting terminals has a bending portion (232, 233) inserted into the cut-away portion (223, 224), and when each of the plurality of the voltage detecting terminals moves in the direction in which the plurality of the batteries are stacked, the bending portion (232, 233) contacts the cut-away portion (223, 224) of each of the plurality of the bus-bars, and restricts movement of each of the plurality of the voltage detecting terminals.