An alternator is vertically mounted to an engine in a vehicle. The engine is arranged such that a crank shaft is vertical with respect to the ground and a crank shaft pulley is fixed to a lower end of the crank shaft such that a rotation axis of the crank shaft pulley is parallel to the crank shaft. The engine is provided with a mounting bracket and the alternator is fixed to the mounting bracket in a condition that an alternator pulley faces downward and electrical components are arranged at the upper portion of the alternator.