An on-foil object color adjustment device includes a data receiver that obtains non-bonded area data relating to a non-bonded area; and a hardware processor that: calculates a ratio of a size of the non-bonded area to a size of the foil area based on the non-bonded area data obtained by the data receiver; calculates, based on the calculated ratio, a color of the non-bonded area, a color of the foil, and color data of an on-foil object, a first influence degree indicating an influence of the non-bonded area on a color of the on-foil object to be printed in the foil area after the foil-bonding; and adjusts the color data of the on-foil object based on the calculated first influence degree.