To provide an engine control unit that can easily realize reacceleration in a jet propulsion boat. In a controller mounted in a jet propulsion boat that jets water pressurized and accelerated by a water jet pump from a rear jet and is propelled by its reaction, in case a throttle angle of an engine narrows in a state in which the speed of the engine that drives the water jet pump is equal to or exceeds a predetermined value, advance angle control is made over the ignition timing of the engine.