Lighting device and projector

A lighting device comprising:

• a light emitting element which outputs light in a first wavelength range;
• a first phase difference plate to which the light output from the light emitting element is input;
• a first polarization separation element which separates the light from the first phase difference plate into a first light flux in a first polarization state, and a second light flux in a second polarization state;
• a wavelength conversion unit which includes a first fluorescent substance layer which is excited by the light in the first wavelength range, and converts the first light flux into a third light flux in a second wavelength range which is different from the first wavelength range;
• an optical element which converts the second light flux into a fourth light flux;
• a first color combining element which combines the third light flux with the fourth light flux;
• a first detection unit which detects an intensity of the third light flux and an intensity of the fourth light flux;
• and
• a first control unit which changes a direction of an optical axis of the first phase difference plate according to a detection result which is obtained by the first detection unit.