A busbar module to be attached to a battery assembly having a stack of a plurality of cells and to connect the plurality of the cells to an external device, the busbar module comprising: a circuit body having a flexible circuit board including a wiring pattern; a plurality of busbars to be connected to corresponding electrodes of the plurality of the cells; and a holder holding the busbars and being extendable in a stacking direction of the plurality of the cells so that the busbars are movable in the stacking direction, the circuit body having: a band-shaped main strip to be located to extend in the stacking direction; a band-shaped first branch strip branched from the main strip and extending toward a corresponding busbar among the plurality of the busbars; and a second branch strip branched from the main strip and extending toward the external device, wherein the main strip, the first branch strip, and the second branch strip are a flexible circuit board, the first branch strip having: a bent portion extending in the stacking direction and having a bent shape around an axis that is crossing the stacking direction and extending parallel with the width direction of the main stripe; and a busbar connection portion disposed closer to an end of the first branch strip than the bent portion and connected to the corresponding busbar, the second branch strip having a device connection portion to be connected to the external device. a circuit body having a flexible circuit board including a wiring pattern; a plurality of busbars to be connected to corresponding electrodes of the plurality of the cells; and a holder holding the busbars and being extendable in a stacking direction of the plurality of the cells so that the busbars are movable in the stacking direction, the circuit body having: a band-shaped main strip to be located to extend in the stacking direction; a band-shaped first branch strip branched from the main strip and extending toward a corresponding busbar among the plurality of the busbars; and a second branch strip branched from the main strip and extending toward the external device, wherein the main strip, the first branch strip, and the second branch strip are a flexible circuit board, the first branch strip having: a bent portion extending in the stacking direction and having a bent shape around an axis that is crossing the stacking direction and extending parallel with the width direction of the main stripe; and a busbar connection portion disposed closer to an end of the first branch strip than the bent portion and connected to the corresponding busbar, the second branch strip having a device connection portion to be connected to the external device. a band-shaped main strip to be located to extend in the stacking direction; a band-shaped first branch strip branched from the main strip and extending toward a corresponding busbar among the plurality of the busbars; and a second branch strip branched from the main strip and extending toward the external device, wherein the main strip, the first branch strip, and the second branch strip are a flexible circuit board, the first branch strip having: a bent portion extending in the stacking direction and having a bent shape around an axis that is crossing the stacking direction and extending parallel with the width direction of the main stripe; and a busbar connection portion disposed closer to an end of the first branch strip than the bent portion and connected to the corresponding busbar, the second branch strip having a device connection portion to be connected to the external device. a bent portion extending in the stacking direction and having a bent shape around an axis that is crossing the stacking direction and extending parallel with the width direction of the main stripe; and a busbar connection portion disposed closer to an end of the first branch strip than the bent portion and connected to the corresponding busbar, the second branch strip having a device connection portion to be connected to the external device.