A battery unit is provided which includes a battery made of a stack of a plurality of cells each of which is equipped with electrode tabs serving as a positive terminal and a negative terminal. The electrode tabs are broken down into first electrode tabs and second electrode tabs. The first electrode tabs are the electrode tabs of every adjacent two of the cells which are joined together through a weld. The second electrode tabs are the electrode tabs of the cells each of which is joined to a bus bar through a weld without being connected to any of the electrode tabs. The first and second electrode tabs each have a bent portion which lies between a body of the cell and the weld and works as a vibration absorber to ensure the stability in forming the weld during a welding operation.