A battery cell (100, 200, 300, 400) having an electrode assembly, configured to have a structure in which separators are disposed respectively between positive electrodes and negative electrodes, mounted in a battery case (120, 220, 320, 420), the battery cell comprising: the battery case comprising an upper case and a lower case, the lower case being provided with a receiving part (130, 230, 330, 430) for receiving an electrode assembly; and the electrode assembly configured to have a stepped structure in which a plurality of electrodes or unit cells (111, 112; 211, 212; 311, 312, 313; 411, 412, 413) is stacked in a height direction on a basis of a plane and at least two of the electrodes or unit cells have different planar sizes, wherein a lowermost electrode (111, 211, 311, 411) stacked at a lowermost layer of the stepped electrode assembly has a large planar size, and at least one electrode or unit cell having a small planar size (112; 212; 312, 313; 412, 413) is stacked on the lowermost electrode, characterized in that the receiving part of the battery case is provided on an inner surface thereof with at least one protrusion (170, 171, 172; 270, 271; 370, 371, 372; 470, 471) protruding toward the electrode assembly in order to prevent movement of at least one of the electrodes or unit cells, the at least one protrusion comprising one or more upper protrusions (170, 171, 172; 270; 370, 371, 372; 470) formed on an upper side surface (126, 226, 326, 426) of the receiving part at which electrode terminals (140, 240, 340, 440) are formed, when viewed from above, the at least one protrusion (170, 171, 172; 270, 271; 370, 371, 372; 470, 471) being located so as to correspond to a side surface of the at least one electrode or unit cell having a small planar size (112; 212; 312, 313; 412, 413). the battery case comprising an upper case and a lower case, the lower case being provided with a receiving part (130, 230, 330, 430) for receiving an electrode assembly; and the electrode assembly configured to have a stepped structure in which a plurality of electrodes or unit cells (111, 112; 211, 212; 311, 312, 313; 411, 412, 413) is stacked in a height direction on a basis of a plane and at least two of the electrodes or unit cells have different planar sizes, wherein a lowermost electrode (111, 211, 311, 411) stacked at a lowermost layer of the stepped electrode assembly has a large planar size, and at least one electrode or unit cell having a small planar size (112; 212; 312, 313; 412, 413) is stacked on the lowermost electrode, characterized in that the receiving part of the battery case is provided on an inner surface thereof with at least one protrusion (170, 171, 172; 270, 271; 370, 371, 372; 470, 471) protruding toward the electrode assembly in order to prevent movement of at least one of the electrodes or unit cells, the at least one protrusion comprising one or more upper protrusions (170, 171, 172; 270; 370, 371, 372; 470) formed on an upper side surface (126, 226, 326, 426) of the receiving part at which electrode terminals (140, 240, 340, 440) are formed, when viewed from above, the at least one protrusion (170, 171, 172; 270, 271; 370, 371, 372; 470, 471) being located so as to correspond to a side surface of the at least one electrode or unit cell having a small planar size (112; 212; 312, 313; 412, 413).