PURPOSE: A ship is provided to improve the stability and propulsion efficiency of the ballast water-free ship. CONSTITUTION: A ship comprises a seawater passing tunnel(100) and a seawater resistance reducing device(200). The seawater passing tunnel is arranged in a hull and comprises an opening part through which seawater passes. The seawater resistance reducing device is partially connected to the seawater passing tunnel to generate electromagnetic force in a direction opposite to a flowing direction of the seawater. Accordingly, the velocity of the flowing seawater is decreased to reduce seawater resistance.
