To obtain a color image excellent in storage stability by using water- base magenta, yellow, cyan, and black inks each of which contains a colorant of which the free acid form is represented by a specific formula and at least one colorant selected from among specific colorants.

A magenta ink used contains a colorant of which the free acid form is represented by formula I (wherein R1 to R3 are each a 1-9C alkyl; and (m) is 0-2); a yellow ink used, a colorant of which the free acid form is represented by formula II (wherein Ar and Ar1 are each aryl, etc.; and L is a divalent linking group, etc.) and other yellow colorants; a cyan ink used, a colorant of which the free acid form is represented by formula II (wherein Pc is a metal-contg. phthalocyanine nucleus; and L1 is a divalent linking group etc.) and other blue colorants; and a black ink used, a colorant of which the free acid is represented by formula IV, V, or VI (wherein A and B are each a benzene ring, a naphthalene ring, etc.; and r is 0 or 1) and other black colorants. Each ink is prepd. by compounding about 0.1-8wt.% colorants, about 45-95wt.% water, about 1-70wt.% hydrophilic org. solvent, about 0.1-10wt.% additives (e.g. urea), and 0.001-5wt.% surfactant.