A battery module (100, 200, 300, 400, 500, 600) comprising: a tray (110, 210, 310, 410, 510, 610) having a battery cell receiving portion formed therein; a first cell assembly (130, 230, 330, 430, 530, 630) being accommodated in the battery cell receiving portion of the tray (110, 210, 310, 410, 510, 610), the first cell assembly (130, 230, 330, 430, 530, 630) being a plurality of battery cells (120, 220, 320, 420, 520, 620) electrically connected to each other and arranged on a single layer; and a second cell assembly (140, 240, 340, 540, 640) being accommodated in the battery cell receiving portion of the tray (110, 210, 310, 410, 510, 610), the second cell assembly (140, 240, 340, 540, 640) being a plurality of battery cells (120, 220, 320, 420, 520, 620) electrically connected to each other and arranged on a single layer, wherein each battery cell (120, 220, 320, 420, 520, 620) includes a cell body (121, 221, 321, 421, 521, 621), first and second electrode leads (1221, 2221, 3221, 5221, 1222, 2222, 3222, 5222) protruding in opposite directions from the cell body (121, 221, 321, 421, 521, 621), and first and second terraces (1211, 2211, 3211, 4211, 5211, 1212, 2212, 3212, 4212, 5212) in regions where the first and second electrode leads (1221, 2221, 3221, 5221, 1222, 2222, 3222, 5222) are connected to the cell body (121, 221, 321, 421, 521, 621), respectively, wherein a plurality of first receiving grooves (131, 231, 331, 431, 531), which are defined by a space where the first electrode lead (1221, 2221, 3221, 5221) and the second electrode lead (1222, 2222, 3222, 5222) of adjacent battery cells (120, 220, 320, 420, 520, 620) of the first cell assembly (130, 230, 330, 430, 530, 630), are provided on one surface of the first cell assembly (130, 230, 330, 430, 530, 630), wherein the cell body (121, 221, 321, 421, 521, 621) of each battery cell (120, 220, 320, 420, 520, 620) of the second cell assembly (140, 240, 340, 540, 640) is accommodated in a corresponding one of the first receiving grooves (131, 231, 331, 431, 531) of the first cell assembly (130, 230, 330, 430, 530, 630), and the cell body (121, 221, 321, 421, 521, 621) of each battery cell (120, 220, 320, 420, 520, 620) included in each of the first and second cell assemblies (130, 230, 330, 430, 530, 630, 140, 240, 340, 540, 640) is arranged on a same layer, and characterized in that an insulating pad (150, 250, 350, 450, 550) and a cooling pad (160, 260, 360, 560) are arranged between the first and second cell assemblies (130, 230, 330, 430, 530, 630, 140, 240, 340, 540, 640). a tray (110, 210, 310, 410, 510, 610) having a battery cell receiving portion formed therein; a first cell assembly (130, 230, 330, 430, 530, 630) being accommodated in the battery cell receiving portion of the tray (110, 210, 310, 410, 510, 610), the first cell assembly (130, 230, 330, 430, 530, 630) being a plurality of battery cells (120, 220, 320, 420, 520, 620) electrically connected to each other and arranged on a single layer; and a second cell assembly (140, 240, 340, 540, 640) being accommodated in the battery cell receiving portion of the tray (110, 210, 310, 410, 510, 610), the second cell assembly (140, 240, 340, 540, 640) being a plurality of battery cells (120, 220, 320, 420, 520, 620) electrically connected to each other and arranged on a single layer, wherein each battery cell (120, 220, 320, 420, 520, 620) includes a cell body (121, 221, 321, 421, 521, 621), first and second electrode leads (1221, 2221, 3221, 5221, 1222, 2222, 3222, 5222) protruding in opposite directions from the cell body (121, 221, 321, 421, 521, 621), and first and second terraces (1211, 2211, 3211, 4211, 5211, 1212, 2212, 3212, 4212, 5212) in regions where the first and second electrode leads (1221, 2221, 3221, 5221, 1222, 2222, 3222, 5222) are connected to the cell body (121, 221, 321, 421, 521, 621), respectively, wherein a plurality of first receiving grooves (131, 231, 331, 431, 531), which are defined by a space where the first electrode lead (1221, 2221, 3221, 5221) and the second electrode lead (1222, 2222, 3222, 5222) of adjacent battery cells (120, 220, 320, 420, 520, 620) of the first cell assembly (130, 230, 330, 430, 530, 630), are provided on one surface of the first cell assembly (130, 230, 330, 430, 530, 630), wherein the cell body (121, 221, 321, 421, 521, 621) of each battery cell (120, 220, 320, 420, 520, 620) of the second cell assembly (140, 240, 340, 540, 640) is accommodated in a corresponding one of the first receiving grooves (131, 231, 331, 431, 531) of the first cell assembly (130, 230, 330, 430, 530, 630), and the cell body (121, 221, 321, 421, 521, 621) of each battery cell (120, 220, 320, 420, 520, 620) included in each of the first and second cell assemblies (130, 230, 330, 430, 530, 630, 140, 240, 340, 540, 640) is arranged on a same layer, and characterized in that an insulating pad (150, 250, 350, 450, 550) and a cooling pad (160, 260, 360, 560) are arranged between the first and second cell assemblies (130, 230, 330, 430, 530, 630, 140, 240, 340, 540, 640).