An illumination device configured to project a predetermined lighting pattern on a surface to be illuminated, comprising: a light source; a collimation lens configured to shape a light from the light source into a parallel illumination light; a diffraction optical element configured to diffract the parallel illumination light so as to project the lighting pattern on the surface to be illuminated; and a collimation-lens drive unit configured to support the collimation lens and drive the same; wherein the collimation-lens drive unit is configured to translate the collimation lens in a predetermined direction that is not parallel to an optical axis of a light incident on the collimation lens, wherein the collimation-lens drive unit is configured to translate the collimation lens along a movement plane that is orthogonal to the optical axis of the light incident on the collimation lens, the illumination device further comprising a magnifying lens disposed between the light source and the collimation lens, wherein: the light source is configured to generate a light beam, the magnifying lens is configured to broaden the light beam so as to generate a divergent light, and the collimation lens is configured to shape the divergent light so as to generate the parallel illumination light, an XYZ three-dimensional coordinate system having an X axis, a Y axis and a Z axis that are orthogonal to one another is defined; the light source is configured to generate the light beam having an optical axis parallel to the X axis; the magnifying lens is configured to generate the divergent light that diverges about the optical axis; the diffraction optical element has an incident plane parallel to a YZ plane; and the collimation-lens drive unit is configured to drive the collimation lens such that the collimation lens is translated along a movement plane parallel to the YZ plane, so that an incident direction of the parallel illumination light with respect to the incident plane is changed by the driving operation. a light source; a collimation lens configured to shape a light from the light source into a parallel illumination light; a diffraction optical element configured to diffract the parallel illumination light so as to project the lighting pattern on the surface to be illuminated; and a collimation-lens drive unit configured to support the collimation lens and drive the same; wherein the collimation-lens drive unit is configured to translate the collimation lens in a predetermined direction that is not parallel to an optical axis of a light incident on the collimation lens, wherein the collimation-lens drive unit is configured to translate the collimation lens along a movement plane that is orthogonal to the optical axis of the light incident on the collimation lens, the illumination device further comprising a magnifying lens disposed between the light source and the collimation lens, wherein: the light source is configured to generate a light beam, the magnifying lens is configured to broaden the light beam so as to generate a divergent light, and the collimation lens is configured to shape the divergent light so as to generate the parallel illumination light, an XYZ three-dimensional coordinate system having an X axis, a Y axis and a Z axis that are orthogonal to one another is defined; the light source is configured to generate the light beam having an optical axis parallel to the X axis; the magnifying lens is configured to generate the divergent light that diverges about the optical axis; the diffraction optical element has an incident plane parallel to a YZ plane; and the collimation-lens drive unit is configured to drive the collimation lens such that the collimation lens is translated along a movement plane parallel to the YZ plane, so that an incident direction of the parallel illumination light with respect to the incident plane is changed by the driving operation. the light source is configured to generate a light beam, the magnifying lens is configured to broaden the light beam so as to generate a divergent light, and the collimation lens is configured to shape the divergent light so as to generate the parallel illumination light, an XYZ three-dimensional coordinate system having an X axis, a Y axis and a Z axis that are orthogonal to one another is defined; the light source is configured to generate the light beam having an optical axis parallel to the X axis; the magnifying lens is configured to generate the divergent light that diverges about the optical axis; the diffraction optical element has an incident plane parallel to a YZ plane; and the collimation-lens drive unit is configured to drive the collimation lens such that the collimation lens is translated along a movement plane parallel to the YZ plane, so that an incident direction of the parallel illumination light with respect to the incident plane is changed by the driving operation.