A multi-functional device comprising: a document mount; a scanner module installed below the document mount so as to be movable in a sub-scanning direction; and a driving unit for moving the scanner module in the sub-scanning direction to scan an object placed on the document mount, the scanner module including: an illuminator to illuminate light to an object on the document mount, a sensor unit to read an image information of an object on the document mount by light reflected from an object on the document mount, wherein the illuminator includes: a light source to emit light, a light source holder to hold the light source, a light guiding unit made of a transparent material, and extending in a main scanning direction perpendicular to the sub-scanning direction to guide light emitted from the light source onto the document mount, a guide holder comprising an installation part to which the light guiding unit is installed and a mounting part to which the light source holder is mounted, the guide holder adapted to hold the light guiding unit and be coupled to the light source holder, wherein the light guiding unit comprises an incident surface facing the light source to receive the light from the light source, a guide surface to reflect the light incident on the incident surface to an exit surface, and an exit surface facing the document mount to allow the light reflected and diffused by the light guiding unit to exit toward the object on the document mount, wherein the guide holder includes a spacer provided inside the installation part to support the light guiding unit. a document mount; a scanner module installed below the document mount so as to be movable in a sub-scanning direction; and a driving unit for moving the scanner module in the sub-scanning direction to scan an object placed on the document mount, the scanner module including: an illuminator to illuminate light to an object on the document mount, a sensor unit to read an image information of an object on the document mount by light reflected from an object on the document mount, wherein the illuminator includes: a light source to emit light, a light source holder to hold the light source, a light guiding unit made of a transparent material, and extending in a main scanning direction perpendicular to the sub-scanning direction to guide light emitted from the light source onto the document mount, a guide holder comprising an installation part to which the light guiding unit is installed and a mounting part to which the light source holder is mounted, the guide holder adapted to hold the light guiding unit and be coupled to the light source holder, wherein the light guiding unit comprises an incident surface facing the light source to receive the light from the light source, a guide surface to reflect the light incident on the incident surface to an exit surface, and an exit surface facing the document mount to allow the light reflected and diffused by the light guiding unit to exit toward the object on the document mount, wherein the guide holder includes a spacer provided inside the installation part to support the light guiding unit. an illuminator to illuminate light to an object on the document mount, a sensor unit to read an image information of an object on the document mount by light reflected from an object on the document mount, wherein the illuminator includes: a light source to emit light, a light source holder to hold the light source, a light guiding unit made of a transparent material, and extending in a main scanning direction perpendicular to the sub-scanning direction to guide light emitted from the light source onto the document mount, a guide holder comprising an installation part to which the light guiding unit is installed and a mounting part to which the light source holder is mounted, the guide holder adapted to hold the light guiding unit and be coupled to the light source holder, wherein the light guiding unit comprises an incident surface facing the light source to receive the light from the light source, a guide surface to reflect the light incident on the incident surface to an exit surface, and an exit surface facing the document mount to allow the light reflected and diffused by the light guiding unit to exit toward the object on the document mount, wherein the guide holder includes a spacer provided inside the installation part to support the light guiding unit. a light source to emit light, a light source holder to hold the light source, a light guiding unit made of a transparent material, and extending in a main scanning direction perpendicular to the sub-scanning direction to guide light emitted from the light source onto the document mount, a guide holder comprising an installation part to which the light guiding unit is installed and a mounting part to which the light source holder is mounted, the guide holder adapted to hold the light guiding unit and be coupled to the light source holder, wherein the light guiding unit comprises an incident surface facing the light source to receive the light from the light source, a guide surface to reflect the light incident on the incident surface to an exit surface, and an exit surface facing the document mount to allow the light reflected and diffused by the light guiding unit to exit toward the object on the document mount, wherein the guide holder includes a spacer provided inside the installation part to support the light guiding unit.