A motorized rear derailleur is basically provided with a base member, a movable member, a pulley arrangement, a motor unit and a power limit circuit. The movable member is movably mounted to the base member between a plurality of gear positions. The pulley arrangement is supported by the movable member. The pulley arrangement includes a pulley having a dynamo that generates electrical energy in response to rotation of the pulley. The motor unit is operatively coupled between the base member and the movable member to selectively move the movable member relative to the base member between the gear positions. The motor unit is electrically coupled to the dynamo to selectively receive electrical energy generated by the dynamo. The power limit circuit is electrically coupled between the dynamo and the motor unit.