To improve propulsive performance of a cargo ship of less than 500 tons gross; and improve environment of a ship crew room.

In a twin-tier deck cargo ship 1 of less than 500 tons gross, the ship crew room 23 is disposed in a region located above an equipment room 22 and sandwiched between a freeboard deck 5 and an upper deck 4. An electric motor 26 for driving a propeller 41 is installed in the equipment room 22. A main engine room 12 is disposed in a region located above the freeboard deck 5 of a bow region 1B. A generator for supplying power to the electric motor 26 is installed in the main engine room 12.