An embodiment of the present invention involves a document reading apparatus that includes an optical scanning unit that moves back and forth in a document reading direction so as to read information of a document placed on a document placement table arranged in a top face of a frame by irradiating the document with light emitted from a light source lamp, and a distribution cable connected to the light source lamp. The optical scanning unit includes a support member that leads out and supports the distribution cable connected to the light source lamp in the document reading direction, and the support member includes a regulating member that regulates inclination of the lead-out distribution cable with respect to the document reading direction to support the distribution cable so as to be substantially parallel to the document reading direction.