TRANSMISSION COIL AND POWER TRANSMISSION APPARATUS

Provided is a transmission coil which can inhibit reduction in transmission efficiency during underwater non-contact electric power transmission. A transmission coil configured to transmit electric power in water includes an annular electric wire through which an alternating current flows, and a first cover which includes non-conductive resin or non-magnetic resin and seals a periphery of the electric wire. The electric wire transmits the electric power via a magnetic field generated by flowing of the alternating current.