A color adjustment apparatus comprising: a color value acquisition unit configured to (i) acquire a first color value of a chart printed on a specified paper as a recommended paper by a desired image forming apparatus, (ii) acquire a second color value of the chart printed on one or more types of unspecified paper by the desired image forming apparatus, and (iii) acquire a third color value of the chart on an arbitrary paper by another image forming apparatus, the arbitrary paper having been used in printing by the other image forming apparatus; a relational expression generation unit configured to obtain, for each of the one or more types of the unspecified paper, a relational expression associating the first color value with the second color value, wherein the relational expression generation unit includes: a learning unit that obtains a learning result for returning from the second color value to the first color value; and a regression function acquisition unit that obtains the relational expression based on the learning result; a paper information registration unit configured to (i) obtain property information of a reference color as at least one of a white color and another solid color in the unspecified paper, and (ii) register an association between the relational expression of each of the one or more types of the unspecified paper and the property information of the reference color; a predicted color value calculation unit configured to calculate a predicted color value of the chart printed on the specified paper by the other image forming apparatus based on the relational expression identified by the property information of the reference color in the arbitrary paper and the third color value, wherein the predicted color value calculation unit includes: an information acquisition unit that obtains the property information of the reference color of the arbitrary paper; a search unit that identifies the relational expression associated with the property information that is one of the same and the most closely related property information of the reference color of the arbitrary paper; and a color value prediction unit that calculates the predicted color value of the chart printed on the specified paper by the other image forming apparatus based on the identified relational expression; and a reproduced color value setting unit configured to set to the other image forming apparatus the predicted color value as a reproduced color value by the desired image forming apparatus a color value acquisition unit configured to (i) acquire a first color value of a chart printed on a specified paper as a recommended paper by a desired image forming apparatus, (ii) acquire a second color value of the chart printed on one or more types of unspecified paper by the desired image forming apparatus, and (iii) acquire a third color value of the chart on an arbitrary paper by another image forming apparatus, the arbitrary paper having been used in printing by the other image forming apparatus; a relational expression generation unit configured to obtain, for each of the one or more types of the unspecified paper, a relational expression associating the first color value with the second color value, wherein the relational expression generation unit includes: a learning unit that obtains a learning result for returning from the second color value to the first color value; and a regression function acquisition unit that obtains the relational expression based on the learning result; a paper information registration unit configured to (i) obtain property information of a reference color as at least one of a white color and another solid color in the unspecified paper, and (ii) register an association between the relational expression of each of the one or more types of the unspecified paper and the property information of the reference color; a predicted color value calculation unit configured to calculate a predicted color value of the chart printed on the specified paper by the other image forming apparatus based on the relational expression identified by the property information of the reference color in the arbitrary paper and the third color value, wherein the predicted color value calculation unit includes: an information acquisition unit that obtains the property information of the reference color of the arbitrary paper; a search unit that identifies the relational expression associated with the property information that is one of the same and the most closely related property information of the reference color of the arbitrary paper; and a color value prediction unit that calculates the predicted color value of the chart printed on the specified paper by the other image forming apparatus based on the identified relational expression; and a reproduced color value setting unit configured to set to the other image forming apparatus the predicted color value as a reproduced color value by the desired image forming apparatus