Abstract: An feeder for an auto mounting device includes a main frame, a blocking mean, an intake assembly, a transmission assembly, an input assembly and a sensor. By the sensor detecting the movement of the auto mounting device and transmitting a signal to activate the transmission assembly, the feeder could be in a normal operation without having an intimate contacting with the auto mounting device. Therefore, the feeder can favorably prevent from tremor and attrition while operating in response to the auto mounting device, conducing to a prompt and regular action of the auto mounting device.