To make high speed navigation of a marine vessel possible by providing propulsion machines on both sides of a hull movably in a vertical direction by lifting means, and constituting each propulsion machine by winding an endless belt with a large number of fins erected on the outer peripheral surface, between a driven wheel and a driving wheel longitudinally spaced and rotatably supported.

During low speed navigation, a propulsion machine 4 formed by winding an endless belt 7 with a large number of fins 12 erected on the outer peripheral surface, between a driven wheel 5 and a driving wheel 6 longitudinally spaced and rotatably supported is placed in a state of being lifted to the upper limit by a lifting means 14. The endless belt 7 of the propulsion machine 4 is rotatory-driven for propulsion, and a direction is changed by changing the rotating speed of lateral endless belts 7 to use the rotational difference. A sharp turn is made by reversing the rotating directions of the lateral endless belts 7 from each other, and backing is performed by reversely rotating the lateral endless belts 7 at the same time. In case of high speed navigation, the propulsion machine 4 is lowered and the endless belts 7 are rotated at high speed.