ILLUMINATION DEVICE AND IMAGE PROJECTION DEVICE

An illumination device including: a light source (11) configured to emit source light; a fluorescence generating unit (16,18) configured to generate fluorescent light by use of the source light from the light source (11) as excitation light; a wavelength selecting unit ((13) configured to alternately place either a first segment or a second segment in a light path, the first segment allowing the source light to pass therethrough, and the second segment reflecting the source light while allowing the fluorescent light to pass therethrough; a polarization converting unit (14) configured to convert polarization of light between linear polarization and circular polarization; and a light guiding unit (15, 17) configured to guide a first linear polarization component and the fluorescent light to the polarization converting unit (14) and to guide a second linear polarization component to the fluorescence generating unit (16, 18). The object is to downsize an illumination device.