A single cylinder engine includes an engine body having a cylinder and a combustion chamber, an intake opening that faces the combustion chamber, and an intake passage in communication with the combustion chamber through the intake opening, a piston provided in the cylinder, an ignition plug arranged in a position within about 5% of a bore diameter of the cylinder from an axis of the cylinder, a throttle valve provided in the intake passage, a sensor that detects an opening degree of the throttle valve, and an ECU that causes the ignition plug to lag in ignition timing during two or three cycles when the throttle valve is increased in opening degree from an idling state.