A light source device includes: a light emitter including a light emitting surface to emit first light having a first wavelength in a light emitting direction; an optical system to condense the first light having the first wavelength at a light condensed position; and a wavelength converter including a wavelength conversion region to convert the first light having the first wavelength to second light having a second wavelength. A center axis of the wavelength converter is parallel to the light emitting surface, the light emitter is at a position adjacent to one end of the wavelength converter in the light emitting direction in a plane orthogonal to the center axis of the wavelength converter, and the light condensed position of the optical system is closer to the light emitter than another end of the wavelength converter opposite to the one end in the light emitting direction in the plane.