To provide an engine control method for a small planing device boat capable of preventing a catalyst from abnormally heating while keeping a planing state of the small planing boat.

The temperature of air discharged from an engine 3 is detected, and fuel injection amount is controlled so as to make an engine speed in a throttle full-opening state between a planing start rotating speed and an engine permissible maximum rotating speed, when the detected discharged air temperature exceeds a set value. In the concrete, all cylinders of the engine 3 are throttled in the fuel injection amount, or at least a part of the cylinders of the engine 3 are made to pause. According to this invention, when the discharged air temperature exceeds the set value, the fuel injection amount is controlled to make the engine speed in the throttle full-opening state between the planing rotating speed and the engine permissible maximum rotating speed, so that the catalyst 21 can be prevented from abnormally heated up by suppressing the discharged air temperature, while keeping a planing state of the small planing boat 1.