A light source device includes a first light source to emit first light having a first wavelength range; a wavelength convertor, disposed on an optical path of the first light, to receive the first light to emit light having other wavelength range different from the first wavelength range; a cyclical movement unit to cyclically move the wavelength convertor while crossing the optical path of the first light; optical parts to define an optical path of the first light, and an optical path of the light emitted from the wavelength convertor; a detector to detect a cyclic movement condition of the cyclical movement unit; and a received light quantity reducing unit to reduce light quantity of the first light received by the wavelength convertor when a cyclic movement condition detected by the detector satisfies an abnormal condition while outputting the first light or the light having other wavelength range to outside.