A head unit is provided that includes a plurality of head groups having a first head and a second head in a direction which crosses a transport direction of a medium. Color difference is obtained which indicates difference in color between patches formed for each band using dots having the same dot diameter from among a plurality of patches based on the result of color measurement performed on a test pattern which includes the plurality of patches for each band, the plurality of patches being formed for each head group using dots having different dot diameters. The amount of first ink and the amount of second ink, which are respectively ejected from the first head and the second head which are included in all the head groups, are adjusted such that the dot diameter becomes the dot diameter which is determined based on the color difference.