A multi-band antenna configured in a portable electrical device capable of operating in a low frequency bandwidth and a high frequency bandwidth has an elongated radiating body and a feeding conductor connecting the elongated radiating body. The feeding conductor has opposite side arms respectively connecting the elongated radiating body and a connecting portion connecting the side arms. A feeding point is arranged at a corner where one of the side arms connects to the connecting portion. The elongated radiating body and the feeding conductor are located on different planes of the portable electronic device. According to the position where the feeding conductor connects to the elongated radiating body and the position where the feeding point is arranged at, the multi-band antenna has a preferred low frequency bandwidth and a preferred high frequency bandwidth. Therefore, the portable electrical device can operate at different wireless bandwidths.