An automatic document feeder includes a transport path member that includes a transport path surface constituting a transport path, and an end portion of which moves in a direction in which it gets away from a feeder body to open the transport path, a support member that is relatively rotatable coaxially with the transport path member, a regulating portion that regulates the relative rotation of the end portion of the transport path member, and an impelling member that impels a portion to be regulated in a direction in which the portion to be regulated contacts the regulating portion, that supports the end portion of the transport path member at a first open position, and that allows the end portion of the transport path member to move to a second open position at which the transport path is opened larger than at the first open position.