Image sensor and image reading apparatus

An image sensor unit comprising:

• a pair of illumination sections each including a light source and light guide to illuminate a document;
• an image sensing element for converting an optical image of the document into an electrical signal;
• a cylindrical lens for focusing the optical image on said image sensing element;
• and
• a frame for integrally holding said illumination sections, said image sensing element, and said lens,
• wherein said illumination sections are so disposed as to sandwich said lens, said light guides have exit ports for making light from said light sources emerge toward the document, and said exit ports are formed such that a peak of exit light is farther than a focal position of said lens for said image sensing element with respect to said image sensing element, and the focal position is included in a beam crossing region of exit beams from said pair of illumination sections.