In an endoscope in which light transmitted from an optical fiber bundle using a positive lens is irradiated as illumination light, a glass rod having a diffusion face disposed on one of end faces is arranged between an aperture diaphragm that adjusts an amount of light from a light source and the optical fiber bundle that guides the light from the aperture diaphragm to a distal end portion of the endoscope, and light without a biased angular component is supplied to the optical fiber bundle so as to eliminate illumination light unevenness.
