To provide a small-sized planning boat having so-called cruise control function allowing cruising at a constant speed or at a constant engine speed without the need for a rider to keep throttle operation.

The jet propelling small-sized planning boat propelled with reaction caused by jetting a water pressurized and accelerated by a water jet pump from a rear jet nozzle comprises a cruise control operating switching SWc so that an engine control unit Ec controls a throttle valve opening/closing actuator Ath for cruising at a prescribed speed or at a predetermined engine speed in response to the operation of the cruise control operating switch SWc.