PURPOSE: To eliminate necessity of landing of a boat when it is not used and to prevent adhesion of barnacles and so on in a flow passage by providing a jet unit with a rotating means in compact structure.

CONSTITUTION: When a driving motor 70 is driven and torque is given to a first rotor 6 through a pinion 7, a second rotor 5 which is integral with it is also rotated, and thus, a water suction port 30 is oriented upward and opposed to an inspection port 9. Cleaning and inspection in a flow passage 37 can be easily carried out from the inspection port 9 in this state. Also, as an impeller housing part 34 and a deflector 8 are also raised with rotation of an impeller shaft 2, fear of invasion of water is reduced. As it is so constituted that a jet unit 3 is rotated using the first rotor 6 and the second rotor 5 and that an opening of the unit 3 is raised with the rotation, invasion of water into the flow passage 37 of the unit 3 during anchorage can be prevented with relatively simple structure.