The present invention relates to an energy supply vessel and an energy supply method using same. The energy supply vessel comprises a hull; an electricity storage device for storing electricity at thehull; a charging port provided at the hull for an electrical connection with an external electricity supply target using electricity as a power source, so as to charge the electricity supply target with the electricity supplied from the electricity storage device; a communication unit provided at the hull so as to allow communication with the electricity supply target; a propeller for generatinga propulsive force such that the hull moves for the electrical connection with the electricity supply target; and a control unit for controlling the electricity storage device, the charging port, thecommunication unit, and the propeller according to an operation signal of an operation unit or a determined process. According to the present invention, electricity can be easily supplied to an electric propulsion ship, an underwater drone, a water drone, an air drone, an electric vehicle, and other various electricity supply targets using electricity as a power source on the water, under the water, or near the water, or a battery can be replaced and, furthermore, a battery in a floatel can be charged, or the energy supply vessel can be used as an uninterruptible power supply device for a floatel, a waterside hotel, or the like. Therefore, the present invention can guarantee stable on-the-water and waterside charging conditions, movement, and electricity use of an electricity supply targetusing electricity as a power source, quickly and conveniently supply electricity to the electricity supply target using electricity as a power source, at any time and at a desired place, and contribute to the recycling of rapidly increasing electric vehicle water batteries.