An adjusting method for endoscope systems comprises a first adjusting step, a second light adjusting step and a storing step. The first adjusting step compares video signals, which are produced from illumination light rays that are reflected from an object and whose wavelengths fall within first, second, and third ranges, with one another, and regulates a lamp current that flows into a light source lamp. The second light adjusting step adjusts a diaphragm that controls an amount of light which is emitted from the light source lamp and which is irradiated to the object. The storing step stores the lamp current regulated at the first adjusting step and a light limiting level adjusted at the second adjusting step.