As a method of sending electric power to underwater vehicles, the contactless power supply system (CLPS) utilizing the cone-type coil is proposed. This system has efficient nature and high power transmission capability, even when the fluctuation in the sea exists. Furthermore, the electromagnetic force generated during power transmission will be useful for maintaining the location of an underwater vehicle stably. If this system is applied to the vehicle, the restriction of a sphere of activity and time in inquiry is go out. So it is possible to reduce in costs. The electric power of 500 W can be transmitted at about 96% of efficiency when the diameter of the coil is 48 mm. And it is calculated for the system to transmit about 2 kW in the same size. Furthermore, it is possible to transmit more electric power by expanding the size of coil