A lighting unit includes LED chips positioned in an array form in a main scanning direction on LED substrates. Cylindrical parabolic mirrors each form a shape in which a cylindrical paraboloid having curvature with respect to an sub-scanning direction has been clipped by an axial plane that is perpendicular to the vertex of the cylindrical paraboloid in the main scanning direction, and project light emitted from the light source on an illumination area of an illuminated item. Each cylindrical parabolic mirror includes an anchoring section that is provided at the vertex of the cylindrical paraboloid, and extends from the vertex in an outside direction of the cylindrical paraboloid. Heat-radiating plates each have a contact section that is in contact with the LED substrate, and a non-contact section. Each LED substrate is interposed between the contact section of the heat-radiating plate and the anchoring section of the cylindrical parabolic mirror.