In order to reduce a power transmission antenna and power receiving antenna of a wireless power supply device for supplying power underwater to a size suitable for an underwater mobile body and sensor, this underwater wireless power supply device 101 wirelessly transmits energy by resonating at a frequency determined by the impedance of a power transmission antenna 103 that transmits energy wirelessly in a good conductor medium 102, the impedance of a power receiving antenna 104 which receives energy transmitted from the power transmission antenna 103, and the impedance of the good conductor medium 102. The power transmission antenna 103 and the power receiving antenna 104 have the multiple antenna coils 105, 106, and at least one dielectric 107, 108 arranged between the multiple antenna coils 105, 106, and the multiple antenna coils 105, 106 each has multiple laminated coils 109.