A light source device according to the present disclosure that is provided with a semiconductor laser unit configured to emit excitation light of a prescribed wavelength, a wavelength conversion unit configured to amplify the excitation light by causing the excitation light to resonate and generate output light of a different wavelength from the excitation light using a prescribed non-linear crystal, the wavelength conversion unit including a first optical path for amplifying the excitation light, and a second optical path for generating the output light, a first servo mechanism configured to control an optical path length of the first optical path, and a second servo mechanism configured to control an optical path length of the second optical path.