We propose a wireless power transfer system using low-frequency magnetic fields. Low-frequency magnetic fields have less effect on the human body and less shielding effect by conductors than high-frequency magnetic fields such as the Qi standard. Therefore, we can explore areas of application in which current high-frequency magnetic field systems cannot be used. The power source is assumed to be a single coil or a Helmholtz coil driven by low-frequency AC current. The power-receiving device has a vibrating beam, which has a Pb(Zr,Ti)O3 (PZT) layer on the surface, and driving magnets. By applying an AC magnetic field, the beam is vibrated similarly to a tuning fork. The driven force is induced as a torque, and the device can operate even in a parallel magnetic field. The device is realized with MEMS technology and has a volume of 20 × 30 × 0.08 mm3, a PZT thickness of 10 µm, and a permanent magnet of 9 × 2 × 2 mm3 attached to it. The device has an output voltage of 3.24 Vrms and an output power of 1.54 mW at an applied magnetic flux density of 0.495 mT.