disclosed is a personal watercraft capable of obtaining a high horsepower in a high engine speed even when a four - cycle engine is mounted in the personal watercraft limited in length . the personal watercraft adapted to eject water from an outlet port to be propelled as the resulting reaction , comprises : a multi - cylinder four - cycle engine contained in an engine room and having even cylinders of four or more cylinders ; a water jet pump being driven by the engine , for pressuring and accelerating the water ; primary collecting exhaust passages , each of which is configured to collect two exhaust passages respectively connected to exhaust ports of two cylinders of the engine into one exhaust passage ; and a secondary collecting exhaust passage configured to collect the primary collecting passages .