PROBLEM TO BE SOLVED: To provide a light source device capable of being comfortably used while retaining the range of adjustment for exposure control even in an endoscope including a light guide with different light transmission characteristics.SOLUTION: A light source device includes a plurality of semiconductor light sources which emit light in first and second wavelength ranges for observation of vascular information respectively. In a vascular information observation mode, a light source control part discriminates models of a plurality of endoscopes and sets driving conditions according to the models, and controls the output of the plurality of semiconductor light sources to retain the ratio of outgoing light amount in the first and second wavelength ranges regardless of the models of the endoscopes. After the output of one light source reaches an upper limit value, the priority is given to exposure control, and the output of the other light source is increased. Then, change of the ratio of outgoing light amount is announced.
