An electronic device includes a battery box receiving two batteries for providing power. The battery box includes a holding base defining two neighboring receiving rooms and a sliding groove and a slidable block slidably installed in the sliding groove to position the batteries in the receiving rooms. The batteries are received in the receiving rooms via passing over the sliding groove. The slidable block includes a retaining shoulder, a positioning portion protruding from one side of the retaining shoulder and used to match with the sliding groove, a stopper plate and a tab connected between the stopper plate and the retaining shoulder. The stopper plate and the tab are protruding from the other side of the retaining shoulder.