PURPOSE: To shorten time required for color matching to sample printing, and to reduce the amount of spoilage required for color matching by a method wherein conversion formula for printing conditions affecting greatly the printing density is renewed constantly, based on the latest data (picture area ratio data or the like), and accuracy of presetting is improved therewith.

CONSTITUTION: A picture area ratio data inputting part 1 receives picture area ratio for each of ink keys in the breadthwise direction of matters to be printed. A set value data inputting part 2 receives set value data for supply amount of ink after color matching to each of the ink keys. A printing condition data inputting part 8 receives printing condition data for printing speed on color matching or the like. A past data renewal/storage device 3 executes constantly renewal and storage of data inputted to each of the parts. A conversion formula computing part 4 calculates conversion formula for seeking ink supply amount setting value from picture area ratio. A preset value computing part 5 calculates ink supply amount in accordance with the conversion formula. Furthermore, an output part 6 for outputting to an ink supply amount adjustment device outputs the preset value.