ILLUMINATION DEVICE

The invention enables a desired projection pattern on a surface to be illuminated, and enables a projection position and/or a projection orientation of the projection pattern to be changed. A laser beam is shaped into a parallel light, and an incident surface of a diffraction optical element recording a hologram image is irradiated with the parallel light. A projection pattern of an arrow oriented in a predetermined direction is projected as a hologram reconstructed image on a surface to be illuminated. An optical-element drive unit rotates the diffraction optical element about a rotation axis in a rotation plane orthogonal to an optical axis of a parallel incident light. By means of the rotation, a geometric positional relationship of the diffraction optical element with respect to the surface to be illuminated is changed, whereby an orientation of the arrow projection pattern on the surface can be changed.