An electronic device, comprising: a housing, wherein the housing comprises: a hinge module; a first housing including a first surface connected to the hinge module and facing in a first direction, a second surface facing in a second direction opposite to the first direction, and a first side member enclosing at least a portion of a first space between the first surface and the second surface; and a second housing including a third surface connected to the hinge module and facing in a third direction, a fourth surface facing in a fourth direction opposite to the third direction, and a second side member enclosing at least a portion of a second space between the third surface and the fourth surface, wherein the second housing is folded with the first housing around the hinge module, wherein the first surface faces the third surface in a folded state, and the third direction is the same as the first direction in an unfolded state; at least one printed circuit board disposed in an internal space of the housing; and a battery pack, wherein the battery pack comprises: a battery cell, wherein the battery cell comprises; a first cell area disposed through the first space; a second cell area extended from the first cell area and disposed through the second space; a foldable area connecting the first cell area and the second cell area; a plurality of base portions (511, 512) stacked to extend from the first cell area to the second cell area through the foldable area and disposed to be electrically insulated through separators; and mixture layers (513, 514) applied to one surface or both surfaces of each of the plurality of base portions (511, 512); and a protective circuit module, PCM, unit extended from at least a portion of the battery cell and disposed to be electrically connected to the printed circuit board, wherein in the foldable area, the mixture layers (513, 514) are omitted, and the foldable area includes a stacked structure of the plurality of base portions (511, 512) and the separators having different lengths. a housing, wherein the housing comprises: a hinge module; a first housing including a first surface connected to the hinge module and facing in a first direction, a second surface facing in a second direction opposite to the first direction, and a first side member enclosing at least a portion of a first space between the first surface and the second surface; and a second housing including a third surface connected to the hinge module and facing in a third direction, a fourth surface facing in a fourth direction opposite to the third direction, and a second side member enclosing at least a portion of a second space between the third surface and the fourth surface, wherein the second housing is folded with the first housing around the hinge module, wherein the first surface faces the third surface in a folded state, and the third direction is the same as the first direction in an unfolded state; at least one printed circuit board disposed in an internal space of the housing; and a battery pack, a hinge module; a first housing including a first surface connected to the hinge module and facing in a first direction, a second surface facing in a second direction opposite to the first direction, and a first side member enclosing at least a portion of a first space between the first surface and the second surface; and a second housing including a third surface connected to the hinge module and facing in a third direction, a fourth surface facing in a fourth direction opposite to the third direction, and a second side member enclosing at least a portion of a second space between the third surface and the fourth surface, wherein the second housing is folded with the first housing around the hinge module, wherein the first surface faces the third surface in a folded state, and the third direction is the same as the first direction in an unfolded state; at least one printed circuit board disposed in an internal space of the housing; and a battery pack, wherein the battery pack comprises: a battery cell, wherein the battery cell comprises; a first cell area disposed through the first space; a second cell area extended from the first cell area and disposed through the second space; a foldable area connecting the first cell area and the second cell area; a plurality of base portions (511, 512) stacked to extend from the first cell area to the second cell area through the foldable area and disposed to be electrically insulated through separators; and mixture layers (513, 514) applied to one surface or both surfaces of each of the plurality of base portions (511, 512); and a battery cell, wherein the battery cell comprises; a first cell area disposed through the first space; a second cell area extended from the first cell area and disposed through the second space; a foldable area connecting the first cell area and the second cell area; a plurality of base portions (511, 512) stacked to extend from the first cell area to the second cell area through the foldable area and disposed to be electrically insulated through separators; and mixture layers (513, 514) applied to one surface or both surfaces of each of the plurality of base portions (511, 512); and a protective circuit module, PCM, unit extended from at least a portion of the battery cell and disposed to be electrically connected to the printed circuit board, wherein in the foldable area, the mixture layers (513, 514) are omitted, and the foldable area includes a stacked structure of the plurality of base portions (511, 512) and the separators having different lengths.