A multi-lamp driving system includes a driving apparatus and a current balancer having detection nodes. The protection apparatus includes at least a detection unit and a determining unit. The detection unit includes first impedance devices and a second impedance device. A first end of each first impedance device is coupled with the corresponding detection node. The second impedance device is coupled with a second end of each first impedance device. The cross-voltage between a first end and a second end of the second impedance device is relative to the sum of the voltage level of the detection nodes coupled with the first impedance devices. The determining unit coupled with the second impedance device of the detection unit outputs a protection signal to disable the driving apparatus according to the cross-voltage between the first and second ends of the second impedance device when at least one of the lamps malfunctions.