Image forming apparatus capable of smoothly feeding large-size sheet into main body

An image forming apparatus including a scanner, which includes a guide member provided at an inlet of a clearance formed below a cover of the scanner. The guide member has a substantially pentagonal shape as viewed from the top, and may also include a notch formed in the top portion of the pentagon. The guide member also includes an edge portion curled in a semicircle in an upward direction that is arranged at both sides of the notch. Further, the curled edge portion is inclined from a center of the clearance toward an edge in a length direction. When an original document having a curled leading edge is fed to the scanner, a central portion of the curled leading edge of the original document is placed beneath the edge portion of the guide member. Thus, when the curled portion of the original document hits the edge portion of the guide member, the curled portion of the original document slips beneath the edge portion while the curled portion of the original document is flattened by the curled edge portion of the guide member.