A processor for an electronic endoscope includes an enhancement processing unit that includes: a depth data generation unit configured to generate depth data D of the entire captured image by generating, a data value representing information on a depth of a concave portion of the living tissue in each pixel; an undulation-enhanced data generation unit configured to generate a value of undulation-enhanced data S, which has information with a steeply inclined change of a signal level value at a boundary between a concave portion and a convex portion of surface irregularities of the living tissue, from the depth data D; and an enhancement processing execution unit that generates an enhanced image by adding or subtracting at least a value to or from a signal level value of the processing target pixel on which the enhancement processing of the captured image is performed.