With a view to providing a light source device and a projector which can rearrange the light collection balance even in the event that the number of illuminated light emitting elements changes as a result of a change in the environment where they are used or in the specifications thereof, a light source device includes a holder 79 having element accommodating portions 79a which each accommodate one of a plurality of light emitting elements and an adjusting portion for moving mechanisms including an optical system such as reflection mirrors and the holder 79 which translate in parallel a center of a whole of optical axes of pencils of light emitted from the plurality of light emitting elements when light is not emitted from part of the plurality of light emitting elements.