A terminal device configured in a system is provided. The system includes a power feeding apparatus and a power receiving apparatus. The power receiving apparatus receives an electric power waveform from the power feeding apparatus through a harness. The power feeding apparatus supplies the power receiving apparatus with an electric power by coupling with the power receiving apparatus. The coupling is conducted by a magnetic field through the harness or an electric field through the harness. The terminal device includes a power conversion portion and a control portion. The power conversion portion is connected to a part of the harness. The control portion controls a power conversion state of the power conversion portion. The control portion controls an input impedance of the power conversion portion to be equal to a characteristic impedance of the harness.