Dispersion containing water-insoluble colorant and production method thereof

A method of producing a dispersion, comprising the steps of:

• dissolving at least two kinds of water-insoluble colorants, a polymer, and a base into an aprotic water-soluble organic solvent, the polymer including at least repeating units of the following A and B as a hydrophilic portion,
• A:
• a repeating unit of having an acid group selected from the group of a carboxylic acid group, a sulfonic acid group, a hydroxyl group, and a phosphoric acid group,
• B:
• a repeating unit selected from the group of repeating units represented by the following formula (1) or (2);
• and
• bringing the solution prepared in the prescribed step into contact with an aqueous medium so as to form water-insoluble colorant fine particles.
• wherein, R1 represents a hydrogen atom or a substituent;
• any one of R2 to R5 represents a single bond to bind to W, and the others each independently represent a hydrogen atom or a substituent;
• J represents —CO—, —COO—, —CONR10—, —COO—, or a methylene group, a phenylene group, or —C6H4CO—;
• R10 represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group;
• W represents a single bond or a divalent linking group;
• A1 represents a heterocyclic group;
• Q1 represents a group of atoms which is necessary for forming a ring together with a carbon atom.