A battery pack including a battery gauge. The battery gauge includes a circuit board, light emitting devices electrically connected to a battery cell on the circuit board and turned on or off according to a voltage of the battery cell, a display unit disposed outside a pack case at positions corresponding to the light emitting devices, and a partition wall guiding light of the light emitting device to a part of the display unit corresponding to the light emitting device. Since the partition wall prevents light of the light emitting device from affecting the neighboring light emitting device, an on/off operation of the light emitting device is accurately displayed on the display unit, so that a battery discharge level can be accurately detected.