A cell voltage measuring apparatus of a battery pack comprises a plurality of multiplexers connected corresponding to each cell group of the battery pack and operated to output a voltage signal of each cell in each cell group based on a reference potential applied from a corresponding cell group; a plurality of floating capacitors connected corresponding to each cell in each cell group and on which the voltage of each cell is charged and held; a switching means for enabling the voltage of each cell to be charged and held on each corresponding floating capacitor; and a controller for controlling the switching means per each cell group to enable the voltage of each cell to be charged and held on each corresponding floating capacitor and controlling each multiplexer to measure the cell voltage held on each floating capacitor of each cell group connected to each corresponding multiplexer.