Illumination device and projector

An illumination device comprising:

• a light source section including a plurality of light emitting devices adapted to emit light in a first wavelength band, and a holding member adapted to hold the plurality of light emitting devices at rotationally symmetric positions;
• a polarization separation element adapted to separate the light emitted from the light source section into a first light beam in a first polarization state and a second light beam in a second polarization state;
• a wavelength conversion device having a wavelength conversion layer to be excited by light in the first wavelength band, and adapted to convert the first light beam into a third light beam in a second wavelength band different from the first wavelength band;
• a conversion optical system adapted to convert the second light beam into a fourth light beam;
• a color combining element adapted to combine the third light beam and the fourth light beam with each other;
• a detection device adapted to detect an intensity of the third light beam and an intensity of the fourth light beam;
• and
• a control device adapted to change a polarization state of the light emitted from the light source section in accordance with a detection result by the detection device.