A secondary battery module comprising: a battery stacked body configured by stacking and placing a plurality of secondary batteries, each having a flat rectangular battery container, so that wide side faces of the secondary batteries, having a large area among side faces of the secondary batteries, are placed opposite each other; a pair of end plates (21, 31) that is respectively disposed at one stacked-direction side of the battery stacked body and at another stacked-direction side of the battery stacked body so as to face opposite each other; a pair of side frames (41, 51) that is respectively disposed at one cell-width-direction side and at another cell-width-direction side so as to face opposite each other, a cell width direction being perpendicular to a stacked direction of the battery stacked body, and one ends of the side frames (41, 51) on the one cell-width-direction side and the other cell-width-direction side engaging with an end plate on the one stacked-direction side and other ends of the side frames (41, 51) engaging with an end plate on the other stacked-direction side; an elastic body that is placed between an end surface of the battery stacked body on the one stacked-direction side and the end plate on the one stacked-direction side and presses the battery stacked body in the stacked direction; protrusions (22L, 22R, 32L, 32R) protruding in the stacked direction are provided on an outside surface of each end plate (21, 31) at the one cell-width-direction side and the other cell-width-direction side; characterized in that: an opening (42, 43) into which a protrusion (22L, 32L) at the one cell-width-direction side is inserted is formed at each of both ends of the side frame (41, 51) on the one cell-width-direction side to engage with the pair of end plates (21, 31) and an edge (42a, 42b) of the opening engages with an inner side of the cell-width-direction of the protrusion (22L, 32L) on the one cell-width-direction side; and an opening (52, 53) into which a protrusion (22R, 32R) on the other cell-width-direction side is inserted is formed at each of both ends of the side frame (41, 51) on the other cell-width-direction side to engage with the pair of end plates (21, 31) and an edge (52a, 52b) of the opening engages with an inner side of the cell-width-direction of the protrusion (22R, 32R) on the other cell-width-direction side. a battery stacked body configured by stacking and placing a plurality of secondary batteries, each having a flat rectangular battery container, so that wide side faces of the secondary batteries, having a large area among side faces of the secondary batteries, are placed opposite each other; a pair of end plates (21, 31) that is respectively disposed at one stacked-direction side of the battery stacked body and at another stacked-direction side of the battery stacked body so as to face opposite each other; a pair of side frames (41, 51) that is respectively disposed at one cell-width-direction side and at another cell-width-direction side so as to face opposite each other, a cell width direction being perpendicular to a stacked direction of the battery stacked body, and one ends of the side frames (41, 51) on the one cell-width-direction side and the other cell-width-direction side engaging with an end plate on the one stacked-direction side and other ends of the side frames (41, 51) engaging with an end plate on the other stacked-direction side; an elastic body that is placed between an end surface of the battery stacked body on the one stacked-direction side and the end plate on the one stacked-direction side and presses the battery stacked body in the stacked direction; protrusions (22L, 22R, 32L, 32R) protruding in the stacked direction are provided on an outside surface of each end plate (21, 31) at the one cell-width-direction side and the other cell-width-direction side; an opening (42, 43) into which a protrusion (22L, 32L) at the one cell-width-direction side is inserted is formed at each of both ends of the side frame (41, 51) on the one cell-width-direction side to engage with the pair of end plates (21, 31) and an edge (42a, 42b) of the opening engages with an inner side of the cell-width-direction of the protrusion (22L, 32L) on the one cell-width-direction side; and an opening (52, 53) into which a protrusion (22R, 32R) on the other cell-width-direction side is inserted is formed at each of both ends of the side frame (41, 51) on the other cell-width-direction side to engage with the pair of end plates (21, 31) and an edge (52a, 52b) of the opening engages with an inner side of the cell-width-direction of the protrusion (22R, 32R) on the other cell-width-direction side.