Each one of code modulators modulates first power to generate a code-modulated wave using a modulation code based on a code sequence, and transmits the code-modulated wave to one of code demodulators. Each one of code demodulator receives the code-modulated wave from one of the code modulators, and demodulates the received code-modulated wave to generate second power using a demodulation code based on a code sequence identical to the code sequence of the modulation code used. When power is transmitted between each one of transmitter and receiver pairs, a controller selects and assigns code sequences to the transmitter and receiver pairs, so as to reduce an average of an absolute value of a total current of the code-modulated waves of the transmitter and receiver pairs in a transmission path, as compared to a reference value, the average being averaged over a predetermined time.