This paper presents the comparison and analysis of the power supply system of a Maglev train and conventional electric railway. Even though all Maglev trains have batteries on their vehicles, electric power supply from the ground side is necessary for levitation, propulsion, on-board electrical equipment, battery recharging, and so on. At low speeds up to $100{\sim}150(km/h)$, the Maglev train, generally, uses a mechanical contact, a current collector as same as conventional electric railway. However, at high speeds, the Maglev train can no longer obtain power from the ground side by using a mechanical contact. Therefore, high speed Maglev trains use their own way to deliver the power to the vehicle from the ground. In this paper, the power supply systems of the german, japanese, and korean low- and high-speed Maglev trains have been reviewed.