To record a high quality image of which the jaggy is inconspicuous in an inkjet recording system.

In an inkjet recorder 100, an image is formed on a plain paper by ejecting ink drops of a pigment type ink that includes at least a pigment, a wetting agent, polyol or glycol ether with a carbon number of 8, an anionic or nonionic surfactant, a water-soluble organic solvent, and water and preferably has a pigment concentration of not less than 6 wt.% and a viscosity of not less than 8 cp (25°C). In order to make a jaggy of a character inconspicuous, a jaggy correction operation is performed for recording a small dot for correction of a jaggy on a contour portion of a binary image such as a character, for example, on a host computer 101.