PURPOSE: To achieve a double inverted propeller ship where the function for changing the direction of ship and the function for improving the propulsion efficiency are combined, by providing a rotatable propeller.

CONSTITUTION: When advancing straight, the propeller shaft 3 will rotate to rotate a propeller 4 thus to produce propulsive force while a pipe 11 is rotated to set a propeller 18 in the direction facing with the propeller 4 thus to rotate the shafts 12, 17 thereby the propeller 18 is rotated reversely against the propeller 4 to produce the propulsive force thus to sail the ship. When changing the direction of ship, the pipe 11 is rotated to direct the propeller 18 oblique forwardly thus to produce the propulsive force which will change the direction of ship.