A document feeder, which may be incorporated in an image forming apparatus, includes a sheet conveying guide, at least one recess, a frame, and at least one protrusion. The sheet conveying guide is disposed facing an exposure glass on an apparatus body and guides an original document passing over the exposure glass when the document feeder is closed to the apparatus body. The recess is disposed on the apparatus body at both ends of the exposure glass in a lateral direction orthogonal to a document conveying direction. The frame is openably closable about one end side of the apparatus body in the lateral direction and vertically movably holds the sheet conveying guide. The protrusion is disposed on the frame facing the recess. The sheet conveying guide and the frame are secured to each other while the recess and the protrusion are engaged with each other in the closed state.