The invention provides an automatic feeder of an electric screw driver, and relates to an auxiliary tool of the electric screw driver. When screws are twisted in daily home decoration, another screw needs to be twisted after one screw is twisted already. The automatic feeder comprises a rotary screw disk, an automatic feeding device and an installation fixing device. Multiple preset screw holes are evenly formed in the rotary screw disk in the circumferential direction. The automatic feeding device comprises an ejector rod, an inner gear sleeve, a spring, a first ratchet-gear wheel and a second ratchet-gear wheel. The first ratchet-gear wheel comprises a round rod. The ejector rod penetrates through the round rod and is fixed to the installation fixing device through a nut. A locking bar is arranged on the round rod and embedded in a locking bar groove. The round rod is sleeved with the second ratchet-gear wheel, and the side cylindrical surface of the second ratchet-gear wheel is fixedly connected with the inner gear sleeve. The installation fixing device comprises an upper fixing body, a lower fixing body and a binding band. According to the technical scheme, multiple screws to be twisted can be conveniently supplied, the next screw is automatically rotated in place after the present screw is twisted through the automatic feeding device, and the automatic feeder is fast and convenient to use.