An image scanning apparatus includes: a feeding unit; an upstream scanning unit that scans an image of one surface of the document; a downstream scanning unit, which is arranged at a downstream side, and which scans an image of the other surface of the document; a memory unit, which stores both data of the upstream scanning unit and data of the downstream scanning unit; and a control unit that controls the document feeding by performing one of a first feeding process and a second feeding process, wherein the first feeding process is a feeding process in which the upstream scanning unit starts to scan a following document while the downstream scanning unit scans a preceding document, and wherein the second feeding process is a feeding process in which the upstream scanning unit starts to scan the following document after the downstream scanning unit scans the preceding document.