a jet - propulsion small watercraft , comprises a water jet pump that pressurizes and accelerates water taken in from outside and ejects the water to propel the watercraft , a steering system configured to steer the watercraft by changing an ejection direction of the water , a steering throttle arm configured to cause a throttle valve of an engine to open , thereby maintaining a steering capability , in response to a closing operation of a throttle lever , an actuator configured to cause the throttle valve in a closed position to open by steering throttle arm , and a spring configured to return the throttle valve to the closed position , wherein the actuator includes a motor configured to be energized at a predetermined motor power value by control of a control device , a reduction mechanism configured to reduce a speed of the motor , and an output shaft configured to be rotated by the reduction mechanism .