Document feeder and image forming apparatus

A document feeder includes an input tray (part of a document placing portion) on which a document is placed, an output tray on which the document output from a document output port in an output direction is stacked, and a substrate including a light source that emits light to the output tray. The output tray is disposed below the input tray. The substrate is fixed to the document placing portion at an oblique angle relative to a horizontal reference of the document feeder such that the optical axis of the light source extends toward the document output port.