An illumination device for use in an endoscope includes a light source, an optical fiber and a wavelength conversion member. The optical fiber guides light to a tip end of an endoscope insertion portion of the endoscope. The wavelength conversion member is provided at an emission end of the optical fiber. The wavelength conversion member configured to be excited by the light source. The illumination device can provide white illumination light obtained by mixing light emitted from the optical fiber and light obtained by exciting the wavelength conversion member by the light emitted from the optical fiber. Also, the illumination device can provide illumination light being different from the white illumination light, by using other excitation light.