A plurality of power storage cells and a plurality of power storage cell holders are stacked alternately in the stacking direction. End plates are superimposed at opposite ends of the power storage cells and power storage cell holders. The end plates are connected by a frame, the frame is covered by an insulator, and the plurality of power storage cells are electrically connected by a bus bar plate, forming a power storage module. Since the surface of the power storage cell is formed from a covered portion covered by the condensation-preventing sheet and a non-covered portion not covered by the condensation-preventing sheet, and the non-covered portion is covered by the power storage cell holder, the insulator, and the bus bar plate, the non-covered portion is covered as much as possible to provide heat insulation, minimizing occurrence of condensed water and preventing formation of a liquid junction.