To provide a propulsion nozzle driving device enabling an fluctuation angle of a propulsion nozzle to be changed provided in a small ship device by grip lever part quickly and surely.

A propulsion nozzle driving device is equipped with a propelling nozzle 5 provided in a rear of a hull in such a way to be fluctuant freely in the vertical direction and produced the propelling power by injecting water behind the hull, wire cables 25, 26 connected with the propulsion nozzle 5, and a grip lever part 10' fluctuating and driving the propulsion nozzle 5 by driving the wire cables 25, 26. Therefore, an input/output conversion mechanism 29 which is fixed to the hull is provided between the wire cables 25 and 26, and the conversion mechanism 29 outputs the input from the grip lever part 10 to the propelling nozzle 5 but does not output the input from the propulsion nozzle 5 to the grip lever 10'.