The invention is a starting and generating apparatus for an engine, including: a rotator configured to be used as a generator driven by an engine as well as used as a starter motor for starting the engine; a power transmission mechanism configured to connect the engine with the rotator; a starter drive unit configured to supply an electricity to the rotator to drive the rotator as the starter motor when the engine is to be started; a clutch mechanism configured to shut off a power transmission from the engine to the power transmission mechanism when the engine is to be started; and a clutch control unit configured to bring the clutch mechanism into a connected state when a rotational speed of the rotator has reached a given rotational speed at which the engine can be started.