A battery module comprising: a block-like battery cell unit in which a plurality of battery cells and a plurality of separators are stacked; first and second frames (90a, 90b; 90), each of which is formed of a single member and restricts the battery cell unit in a stacking direction of the battery cells and the separators, wherein the frames are rectangular and larger than an end face of the battery cell unit, each of the frames (90a, 90b; 90) comprising four angular portions which are opposed to angular portions of end separators located at respective ends of the battery cell unit, as viewed in the stacking direction, and which define gaps with reference to the angular portions of the end separators, the end separators each comprising an end plate and two side portions integrally extending in the same direction from the opposite two sides of the end plate, wherein each of the frames (90a, 90b; 90) further includes four peripheral walls, wherein of the four peripheral walls, a pair of longer peripheral walls opposed to each other are made to face band portions and the side portions of the separators in the fitted state of the frames, wherein each of the four peripheral walls is provided with a tapered introduction plate on one side thereof, the introduction plate extending in the longitudinal direction of the peripheral wall and being bent outward; and rectangular plates which are provided adjacent to the end separators at the respective ends and are located between the battery cells and the end plates of the end separators at the respective ends, the rectangular plates having such rigidity that prevents the rectangular plates from being curved when the rectangular plates are pressed by a load generated by an increase in internal pressure of the battery cells. a block-like battery cell unit in which a plurality of battery cells and a plurality of separators are stacked; first and second frames (90a, 90b; 90), each of which is formed of a single member and restricts the battery cell unit in a stacking direction of the battery cells and the separators, wherein the frames are rectangular and larger than an end face of the battery cell unit, each of the frames (90a, 90b; 90) comprising four angular portions which are opposed to angular portions of end separators located at respective ends of the battery cell unit, as viewed in the stacking direction, and which define gaps with reference to the angular portions of the end separators, the end separators each comprising an end plate and two side portions integrally extending in the same direction from the opposite two sides of the end plate, wherein each of the frames (90a, 90b; 90) further includes four peripheral walls, wherein of the four peripheral walls, a pair of longer peripheral walls opposed to each other are made to face band portions and the side portions of the separators in the fitted state of the frames, wherein each of the four peripheral walls is provided with a tapered introduction plate on one side thereof, the introduction plate extending in the longitudinal direction of the peripheral wall and being bent outward; and rectangular plates which are provided adjacent to the end separators at the respective ends and are located between the battery cells and the end plates of the end separators at the respective ends, the rectangular plates having such rigidity that prevents the rectangular plates from being curved when the rectangular plates are pressed by a load generated by an increase in internal pressure of the battery cells.