Light source apparatus and projector

A light source apparatus comprising:

• a light emitting device that has a first light emitting region and a second light emitting region and outputs excitation light of a first wavelength band;
• a phosphor layer that is so provided that the phosphor layer coincides with the first light emitting region in a plan view and emits light of a second wavelength band different from the first wavelength band when irradiated with first excitation light outputted from the first light emitting region;
• a reflection element that is provided on the opposite side of the phosphor layer to the light emitting device, transmits light of the second wavelength band, and reflects light of the first wavelength band;
• and
• a light guide section that is disposed on an optical path between the phosphor layer and the reflection element, transmits second excitation light outputted from the second light emitting region and light outputted from the phosphor layer, and guides the second excitation light reflected off the reflection element in such a way that at least part of the reflected second excitation light is incident on the phosphor layer.