An image reading apparatus, a document supply device thereof and methods thereof may reduce a scanning operation time. A document supply device may include a holding position (e.g., internal) for a following document such that a scanning time between documents may be reduced. The document supply device may include a main feed path to guide an introduced document, a simplex path coupled to the main feed path and to guide the document fed through the main feed path to the scanning window to scan one document surface (e.g., first surface), a duplex path to guide the document having passed the scanning window to the simplex path to scan the other document surface (e.g., second surface), an auxiliary supply path coupled to the main feed path and the simplex path where the document fed through the main feed path temporarily stands by before being fed to the scanning window.