An automatic document feeder for electric equipment includes an input tray, a driving mechanism, and a block mechanism. The input tray has a receiving end, a discharge end, and a first path extending from the receiving end to the discharge end. The driving mechanism includes a separating-roller shaft disposed above the input tray and in proximity to the discharge end, and a separating roller sleeved fixedly on the shaft. The blocking mechanism includes a blocking member pivotable between a blocking position whereat the blocking member is disposed on the first path, and a non-blocking position whereat the blocking member is removed from the first path. A driven arm is connected to and co-rotatable with the separating-roller shaft so as to pivot the blocking member between the blocking position and the non-blocking position.