A power supply system is provided, having: a primary side coil; a power transmission apparatus having a primary side circuit for feeding a pulse voltage resulted from switching a DC voltage which is obtained by rectifying and smoothing a commercial power supply to the primary side coil; a secondary side coil magnetically coupled to the primary side coil; and power reception equipment having a secondary side circuit for rectifying and smoothing voltage induced across the secondary side coil, wherein there is provided a power adjusting section for adjusting a level of power to be transmitted according to power required by the power reception equipment. The power adjusting section has, in the primary side circuit, a carrier wave oscillation circuit for supplying a carrier wave to the primary side coil, a demodulation circuit for demodulating a modulated signal transmitted from the secondary circuit and received by the primary side coil, and a power change-over section for selecting a level of power to be transmitted according to an information signal from the power reception equipment and demodulated by the demodulation circuit. The power adjusting section has, in the secondary side circuit, a modulation circuit for modulating the carrier wave fed from the carrier wave oscillation circuit and received by the secondary side coil with the information signal from the power reception equipment and transmitting the modulated signal.