An image reading apparatus for generating image data corresponding to a document image, includes: an irradiating section for irradiating light rays to an image bearing surface of a document; a housing formed with a slit for restrictedly passing light rays reflected from the image bearing surface of the document; a photoelectric conversion element for converting an optical image made of the light rays having passed through the slit of the housing to an electric signal; and an optical system for guiding the light rays having passed through the slit of the housing to the photoelectric conversion element. The housing has a light restrictor at each of the both ends of the slit. The light restrictor projects toward the image bearing surface of the document to thereby keep light rays reflected from an area outside a reading area of the image bearing surface of the document from entering the slit.