To make the ratio of impact concentrations of droplets, ejected from nozzle arrays, on an ejection target material as designed, even when environmental conditions are changed.

Color adjust IDs represent ratios of ejection amounts of ink droplets between nozzle arrays. A control unit corrects the color adjust IDs according to the environmental temperature obtained by a temperature sensor and ejection amount information about ejection amounts of the ink droplets corresponding to the environmental conditions. Then, according to the corrected color adjust IDs, the control unit adjusts dot formation ratio on recording paper for each nozzle array.