To provide a color conversion device that suppresses collapse of gradation and improves color tones, an image processing device, an image forming apparatus, a color conversion method, and a color conversion program.

A color conversion device performs gamut mapping processing in which image output means maps an input color signal in a reproducible gamut. The color conversion device includes: line input means for extracting from the color signal an input line including a plurality of input points on a line that connects a white point or a black point and any chromatic color; input line adjustment means for calculating an evaluation value that evaluates a color tone for every input point that makes up the input line, and when the evaluation value is smaller than a pre-defined reference value, adjusting a chromaticity value of the input points so that the evaluation value is no less than the reference value; and mapping means for causing the image output means to perform gamut mapping in the reproducible gamut based on the adjusted input line.