A light source device for a spectrophotometer includes a light source chamber, a light source retained in the light source chamber and having an electrode therein for generating light, an electrode support part connected to the electrode and extending outside the light source chamber, and a cover disposed around the electrode support part for covering a portion of the electrode support part situated outside the light source chamber. A cooling mechanism is installed for cooling the light source chamber from an outside thereof so that the light source is not directly cooled by means of the cover. The spectrophotometer includes the light source device.