The invention provides an aqueous ink composition, which comprises at least: 1) an alkali neutralized product of a copolymer containing constituent units of: (i) at least one monomer selected from the group consisting of alkene, styrene, styrene derivatives, vinyl naphthalene, and vinyl naphthalene derivatives; (ii) at least one monomer selected from monomers containing an acidic group that ion dissociate; and (iii) at least one .alpha.,.beta.-ethylenic unsaturated carboxylic acid alkyl ester; 2) a pigment; and 3) an aqueous medium, wherein the alkali neutralized product of the copolymer in the aqueous ink composition forms micelle aggregations with an average diameter being set in the range of 10 nm to 300 nm. A manufacturing method of the aqueous ink composition and an image forming method using the aqueous ink composition are also provided.