A color signal processing apparatus which performs a linear matrix transformation includes: an approximate coefficient storage unit that stores approximate coefficients of approximate expressions, which approximate values of the matrix coefficients, respectively, and in which a value of a first color among three primary colors of RGB is made a variable, a matrix coefficient calculation unit that calculates 3×3 matrix coefficients according to an input RGB signal by substituting a value of the first color in the input RGB signal for the approximate expressions given by the approximate coefficients readout from the approximate coefficient storage unit; and a conversion unit that performs color conversion by multiplying the input RGB signal by the matrix coefficients calculated by the matrix coefficient calculation unit, and outputs color-converted RGB signal.