A light source apparatus includes: a white LED that emits light including a first wavelength band and a second wavelength band； a violet LED that emits light in a third wavelength band, and a rotating disk including a filter that transmits light in the first wavelength band. The light source apparatus also includes a rotating disk drive section that changes a position of the rotating disk so that if a normal observation mode is selected, the filter is retracted from an optical path of the light emitted from the white LED, if a narrow band observation mode is selected, a filter is continuously inserted in the optical path of the light emitted from the white LED, and if a twin mode is selected, the filter is intermittently inserted in the optical path of the light emitted from the white LED.
