Provided is an illumination device in which loss of light intensity is small and deterioration of directivity is prevented. Provided is an illumination device including at least one white light source that emits white light a first light guiding unit that is disposed on an emission optical axis of the white light source and that guides the white light emitted from the white light source outward in a radial direction perpendicular to the emission optical axis a second light guiding unit that is arrayed with the first light guiding unit in a direction along the emission optical axis and that guides light going inward in the radial direction in the direction along the emission optical axis a rotating unit that rotationally drives the first light guiding unit and the second light guiding unit together about the emission optical axis a plurality of semiconductor light sources that are disposed outward of the second light guiding unit in the radial direction and arrayed in a circumferential direction about the emission optical axis and that emit illuminating light inward in the radial direction and a plurality of wavelength-range selecting units that are disposed outward of the first light guiding unit and the second light guiding unit on opposite sides in the radial direction at circumferential positions different from those of the semiconductor light sources and that select light components in predetermined wavelength ranges from the white light guided by the first light guiding unit and return the light components to the second light guiding unit.
