A battery module comprising: An individual cell configures with a power generating element formed by stacking a positive electrode and a negative electrode with a separator therebetween and sealed by a cladding material (laminated sheet 20); and a housing including a pair of cases that sandwich the individual cell from two sides in a stacking direction, wherein at least one of the pair of cases comprises: a bulging portion that is formed so as to be curved and to protrude toward the individual cell, and presses the individual cell, a first extension portion that is formed so as to extend from outer periphery of the bulging portion in a direction that intersects with the stacking direction, an inclined portion that is formed so as to extend from the outer periphery of the first extension portion while bending or curving toward the individual cell, and a second extension portion that extends from the outer periphery of the inclined portion along a direction that intersects with the stacking direction, characterized in that the housing further including a reinforcing member (122, 123) formed so as to have a plate shape that reinforces the cases by being joined to at least one of the pair of cases, and in that the second extension portion of the cases being joined to the reinforcing member (122, 123). An individual cell configures with a power generating element formed by stacking a positive electrode and a negative electrode with a separator therebetween and sealed by a cladding material (laminated sheet 20); and a housing including a pair of cases that sandwich the individual cell from two sides in a stacking direction, wherein at least one of the pair of cases comprises: a bulging portion that is formed so as to be curved and to protrude toward the individual cell, and presses the individual cell, a first extension portion that is formed so as to extend from outer periphery of the bulging portion in a direction that intersects with the stacking direction, an inclined portion that is formed so as to extend from the outer periphery of the first extension portion while bending or curving toward the individual cell, and a second extension portion that extends from the outer periphery of the inclined portion along a direction that intersects with the stacking direction, characterized in that the housing further including a reinforcing member (122, 123) formed so as to have a plate shape that reinforces the cases by being joined to at least one of the pair of cases, and in that the second extension portion of the cases being joined to the reinforcing member (122, 123). a bulging portion that is formed so as to be curved and to protrude toward the individual cell, and presses the individual cell, a first extension portion that is formed so as to extend from outer periphery of the bulging portion in a direction that intersects with the stacking direction, an inclined portion that is formed so as to extend from the outer periphery of the first extension portion while bending or curving toward the individual cell, and a second extension portion that extends from the outer periphery of the inclined portion along a direction that intersects with the stacking direction, characterized in that the housing further including a reinforcing member (122, 123) formed so as to have a plate shape that reinforces the cases by being joined to at least one of the pair of cases, and in that the second extension portion of the cases being joined to the reinforcing member (122, 123).