To enhance print quality by mixing a high density ink and a low density ink in a printer using a shading ink.

A decision is made whether a dark dot is formed or not with reference to a recording rate table of high density ink from inputted gradation data, and a dark dot is formed by driving a piezoelement PE of that ink head if a decision is made that a dark dot is formed otherwise a decision is made whether a dot is formed with a low density ink or not and on/off of a light dot is determined such that an average recording rate has a specified value. Since formation of a dark dot has been started in a region of referred table lower than gradation data where the recording rate of light dot has a maximum value, colors are mixed smoothly at a seam from light dot recording to dark dot recording and print quality can be enhanced extremely. Recording rate of light dot may be varied depending on the density of magenta at a position corresponding to the recording position of cyan ink.