A ship that reduces the total amount of fossil fuels and other energy sources required, thereby saving energy. The ship (1) has a plurality of subsystems (10) constructed by dividing a network of power supply lines (3) and signal lines (4) into groups. The subsystems (10) consist of at least two subsystems among a bridge subsystem (10a) on the bridge; a propulsion subsystem (10b) in an engine room; a deck subsystem (10c) installed on a deck; a ballast cargo subsystem (10d) for ballasting and equipment installed in a hold; and an information processing subsystem (10e) corresponding to communication equipment. The subsystems (10) each have a storage battery (5) and a smart meter (6), each of which is linked to a microgrid monitoring and control system (2), which detects the amount of electric power consumed by the subsystems (10), and controls the transfer of electric power between the subsystems.