This study examined a novel intra-body communication method using magnetic coupling. In order to design a communication device using magnetically coupled intra-body communication, it is important to well understand the signal path loss characteristics in a human body and develop a technology so as to minimize its path loss. This study calculated the signal path loss in a variety of magnetic couplings by computer simulation. The magnetic couplings analyzed include normal inductive coupling (non-resonant coupling) and two types of resonant couplings. The 3D finite element model incorporating circuit elements was used for the examination. Results of the frequency characteristics of the signal path loss reveal that the optimal frequency band was between 2 MHz and 4 MHz for inductive coupling. In addition, one of the resonant couplings could improve the signal path loss by approximately 20 dB at a resonant frequency of 2 MHz. Also, in order to verify the validity of the simulation results, this study actually measured the signal path loss. As a result, it was confirmed that the simulation and the measurement results almost agreed.