Illuminating device, image reading apparatus and image forming apparatus

An illuminating device comprising:

• a light-emitting element;
• a substrate on which the light-emitting element is mounted;
• and
• a light-guiding member,
• wherein the light-emitting element is disposed so as to face an end portion of the light-guiding member in a longitudinal direction, and light from the light-emitting element is made incident upon the end portion in the longitudinal direction,
• wherein the light-guiding member guides the light inside so as to illuminate an illumination target from a light emitting face along the longitudinal direction of the light-guiding member, and
• wherein the illuminating device includes
• a facing member that is arranged so as to face a light-emitting element-mounted surface of the substrate and that is provided with a through hole for passing the light from the light-emitting element to the end portion of the light-guiding member, and
• a radiator member that is arranged so as to face a surface of the substrate, the surface being opposite to the light-emitting element-mounted surface.