A multi-band antenna system is provided to enhance the operation performance of the antenna at respective frequency bands by tuning a resonance frequency at a communication frequency. A multi-band antenna system includes a resonance frequency selector(10), a switching unit(20), and a high-frequency selector(30). The resonance frequency selector tunes the resonance frequency of the antenna to a communication frequency band by controlling first and second frequency select signals. The first frequency select signal is used to select one of high and low frequency bands. The second frequency select signal is used to select one of finely-tuned high frequency bands. The switching unit selects one of the high and low frequency bands based on the first frequency select signal. When the high frequency band is selected, the high-frequency selector manipulates antenna conductors to adjust a length of the antenna based on the second frequency select signal such that one of the finely-tuned high frequency bands is selected.