A battery pack, comprising: a cell module assembly having battery cells arranged to be stacked, a cell case accommodating the battery cells, and first positive and negative electrode bus bars (120a,b) electrically connected to the battery cells and having one end extending to the outside of the cell case; a BMS assembly having a BMS circuit board, a current sensor unit vertically fixed to an edge of the BMS circuit board, and a BMS housing supporting the BMS circuit board, the BMS assembly being provided so that a lower portion of the BMS housing is coupled to the cell case; and a pack cover having positive and negative electrode terminals (310, 320) and second positive and negative electrode bus bars (330a,b) electrically connected to the positive and negative electrode terminals (310, 320) respectively, the pack cover being configured to cover an upper portion of the BMS housing, wherein the first negative electrode bus bar and the second negative electrode bus bar respectively have one end vertically connected to the current sensor unit; wherein the current sensor unit includes: a shunt provided in the form of a plate-shaped metal resistor connected to the first negative electrode bus bar and the second negative electrode bus bar and having bolting holes formed in both ends thereof, the shunt being vertically disposed with respect to the BMS circuit board; and a shunt support member configured to clamp the shunt to be erect vertically and, the shunt support member being fixedly coupled onto the BMS circuit board; and wherein BMS circuit board has a shunt installation portion formed at one side of the edge thereof and screwed to the shunt support member, and both side portions of the BMS circuit board based on the shunt installation portion are torn off to form an empty space as much as at least a length of the shunt; and wherein a horizontal surface of the BMS housing has a bus bar access portion formed by opening a lower portion thereof below the shunt so that the first negative electrode bus bar is directly coupled to the shunt at a location right below the shunt. a cell module assembly having battery cells arranged to be stacked, a cell case accommodating the battery cells, and first positive and negative electrode bus bars (120a,b) electrically connected to the battery cells and having one end extending to the outside of the cell case; a BMS assembly having a BMS circuit board, a current sensor unit vertically fixed to an edge of the BMS circuit board, and a BMS housing supporting the BMS circuit board, the BMS assembly being provided so that a lower portion of the BMS housing is coupled to the cell case; and a pack cover having positive and negative electrode terminals (310, 320) and second positive and negative electrode bus bars (330a,b) electrically connected to the positive and negative electrode terminals (310, 320) respectively, the pack cover being configured to cover an upper portion of the BMS housing, wherein the first negative electrode bus bar and the second negative electrode bus bar respectively have one end vertically connected to the current sensor unit; wherein the current sensor unit includes: a shunt provided in the form of a plate-shaped metal resistor connected to the first negative electrode bus bar and the second negative electrode bus bar and having bolting holes formed in both ends thereof, the shunt being vertically disposed with respect to the BMS circuit board; and a shunt support member configured to clamp the shunt to be erect vertically and, the shunt support member being fixedly coupled onto the BMS circuit board; and wherein BMS circuit board has a shunt installation portion formed at one side of the edge thereof and screwed to the shunt support member, and both side portions of the BMS circuit board based on the shunt installation portion are torn off to form an empty space as much as at least a length of the shunt; and wherein a horizontal surface of the BMS housing has a bus bar access portion formed by opening a lower portion thereof below the shunt so that the first negative electrode bus bar is directly coupled to the shunt at a location right below the shunt.