CONTACTLESS POWER TRANSMISSION SYSTEM FOR TRANSMITTING POWER FROM POWER TRANSMITTER APPARATUS TO POWER RECEIVER APPARATUS, AND SUPPLYING LOAD DEVICE WITH DESIRED VOLTAGE

A detection circuit detects at least one of a value of a current flowing through a power transmitting coil, and a value of a current or voltage generated by an auxiliary coil. A control circuit determines a transmitting frequency based on the value detected by the detection circuit, the transmitting frequency at least locally minimizing load dependence. The control circuit determines a voltage for the transmitting power at which an output voltage of a power receiver apparatus is equal to a predetermined target voltage when generating the transmitting power having the transmitting frequency determined, and controls the power supply circuit to generate the transmitting power having the transmitting frequency and voltage determined.