An image reader and document conveying method shorten times necessary for a discharge process that discharges a document in being conveyed and for an idle feeding process of a document that is left on a paper feed tray.If during double-sided reading, a stop key is operated to issue an instruction to cancel reading, a conveyance controller outputs a path specifying signal to select a single-sided path, and thereby a conveyance route is switched from a double-sided path to the single-sided path. For this reason, the discharge process that discharges a document being conveyed at the time of the reading cancellation to a paper discharge tray, and the idle feeding process that discharges a document left on a paper feed tray to the paper discharge tray are performed with use of the single-sided path that is shorter than the double-sided path, and therefore the times necessary for the discharge and idle feeding processes can be shortened.