An image reading apparatus includes a stacking portion, a feeding unit, a reading unit, and a discharge portion provided below the stacking portion. The feeding unit feeds a sheet stacked on the stacking portion in a feeding direction. The reading unit reads an image on the fed sheet and the discharge portion discharges the read sheet. The stacking portion includes first and second support surfaces that support the sheet and first and second regulating units to regulate a position of the sheet in a widthwise direction using two opposing ends of the sheet. The second support surface is retractable from a predetermined section above the discharge portion. The first support surface includes a downstream support portion that supports the sheet on a downstream side of the predetermined section in the feeding direction. A part of the second regulating surface is positioned on the downstream support portion.