To dispose a propeller shaft and an exhaust pipe in low positions, to reduce the gravity center of a ship body and to reduce the size of the ship body in a height direction.

In a small ship propelled by transmitting the motive force of an engine 2 to a water jet propeller disposed in the rear end part of a propeller shaft disposed in the longitudinal direction of a sip body and jetting water in a rear direction, the output shaft 2a of the engine 2 is disposed by being made eccentric to one side of the engine 2 in parallel with the propeller shaft, the propeller shaft is connected to the output shaft 2a of the engine 2 via transmission mechanisms 2k, 2i and 2m, and an exhaust pipe 6 provided so as to be extended from the engine 2 toward the rear side of the ship body is disposed in a side opposite the propeller shaft sandwiching the engine 2.