An image scanning unit an image forming apparatus having the same to scan an image recorded on a document. The image scanning unit includes: a transparent window on which a document to be scanned is laid; an image sensor running straightly under the transparent window for capturing an image recorded on the document, a unit for driving the image sensor; a guide shaft for guiding the straight movement of the image sensor; and an image sensor carrier connected to the driving unit and the guide shaft for straightly moving the image sensor along the guide shaft when the driving unit operates. The image sensor carrier has an image sensor mounting surface on which the image sensor is mounted, and a guide shaft holder integrally formed with the image sensor mounting surface and mounted on the guide shaft.