A mobile device having a periphery and including a substrate, a feeding line, and a resonance element is provided. The substrate has a ground plane and the feeding line is disposed on the substrate. The resonance element is formed on at least a portion of the periphery. The resonance element is electrically connected to the feeding line and the ground plane respectively via a first feeding point and a first ground point, so as to form a first excitation path. The resonance element receives and transmits a first radio frequency signal and a second radio frequency signal via the first excitation path.