To provide a small planing boat with the structure that the propelling force of an water jet pump is effectively improved by the improvement of output of an engine (increased engine speed).

In this small planing boat with the structure that the water pressurized and accelerated by the water jet pump P driven by the engine E is injected backward to propel the planing boat with a reaction, a reduction gear 1 is arranged between a crank shaft 26 of the engine E and the water jet pump P.