To improve control accuracy by providing a cam angle detecting means and a crank angle detecting means, measuring an output interval time between angle signals from the crank angle detecting means so as to provide an engine rotational speed, determining a cylinder of an engine, and controlling ignition timing and fuel injection timing.

An outboard motor is provided with a controller 50 for controlling an engine, and the controller 50 inputs output signals from a cam angle detecting means 51 outputting a reference signal on the basis of the rotation of a cam shaft and from a crank angle detecting means 52 which outputs an angle signal matching with a crank angle on the basis of the rotation of a crank shaft so as determine a cylinder on the basis of a pulse of the crank angle signal from a reference pulse. By means of the controller 50, a crank angle for each cylinder is provided from the output of the angle signal to the reference signal, while an output time interval between the angle signals is measured and an engine rotational speed is provided, and a cylinder in the engine is determined, so that ignition timing and fuel injection timing are controlled on the basis of the crank angle and the engine rotational speed.