An electronic endoscope signal-processing device is provided that includes a gradation compensation processor. The gradation compensation processor compensates for R, G, and B gradations by controlling R, G, and B tone curves defining relationship between input values and output values of each of the R, G, and B signals. The R tone curve is shaped so as to squash the output values of the R Signal when the R signal input values are in a relatively low range and to expand the output values when the input values are in a relatively high range.
