A battery module comprising: a battery block composed of a plurality of battery cells; and a voltage detecting circuit for detecting a voltage between terminals of each of said battery cells, wherein a flexible printed circuit board, in which a voltage detecting line for electrically connecting a positive electrode terminal or a negative electrode terminal of each of said battery cells and said voltage detecting circuit is integrated with a substrate made of a flexible material, is attached to said battery block, characterized in that said battery block includes said plurality of battery cells that are stacked, a first terminal row in which one of the positive electrode terminal and the negative electrode terminal of each of the battery cells is arranged in a direction in which said battery cells are stacked is constituted, and a second terminal row in which the other terminal of each of the battery cells is arranged in the direction in which said battery cells are stacked is constituted, and said flexible printed circuit board is composed of a first flexible printed circuit board having a plurality of voltage detecting lines each connecting the terminal constituting said first terminal row and said voltage detecting circuit, and a second flexible printed circuit board having a plurality of voltage detecting lines each connecting the terminal constituting said second terminal row and said voltage detecting circuit, wherein said first flexible printed circuit board is arranged along said first terminal row, and said second flexible printed circuit board is arranged along said second terminal row. a battery block composed of a plurality of battery cells; and a voltage detecting circuit for detecting a voltage between terminals of each of said battery cells, wherein a flexible printed circuit board, in which a voltage detecting line for electrically connecting a positive electrode terminal or a negative electrode terminal of each of said battery cells and said voltage detecting circuit is integrated with a substrate made of a flexible material, is attached to said battery block, characterized in that said battery block includes said plurality of battery cells that are stacked, a first terminal row in which one of the positive electrode terminal and the negative electrode terminal of each of the battery cells is arranged in a direction in which said battery cells are stacked is constituted, and a second terminal row in which the other terminal of each of the battery cells is arranged in the direction in which said battery cells are stacked is constituted, and said flexible printed circuit board is composed of a first flexible printed circuit board having a plurality of voltage detecting lines each connecting the terminal constituting said first terminal row and said voltage detecting circuit, and a second flexible printed circuit board having a plurality of voltage detecting lines each connecting the terminal constituting said second terminal row and said voltage detecting circuit, wherein said first flexible printed circuit board is arranged along said first terminal row, and said second flexible printed circuit board is arranged along said second terminal row.