A power generator according to the present invention includes: a power generating section (101) for outputting DC energy; an oscillator (103) for converting the DC energy into RF energy having a frequency f0; a first antenna (107) for transmitting the RF energy; a second antenna, which receives, by coupling a resonant magnetic field, at least a part of the RF energy transmitted by the first antenna (107); and an output converting section (120) for converting the RF energy supplied from the second antenna (109) into AC energy having a lower frequency than the RF energy. If the oscillator (103) has a voltage step-up ratio Voc, the output converting section (120) has a voltage step-up ratio Vtr, the first inductor (107a) of the first antenna (107) has an inductance L1, the second inductor (109a) of the second antenna (109) has an inductance L2, and the first and second antennas (107, 109) have a coupling coefficient k, the power generator satisfies (L2/L1)≧(k/(Voc×Vtr))2.