wherein the graft copolymer is formed by suspension polymerization or emulsion polymerization of a styrenic, methacrylic or acrylic monomer with an amphiphilic block copolymer having a hydrophilic block segment having a repeating unit structure represented by General Formula (1) shown below and a hydrophobic block segment having a repeating unit structure represented by general formula (2) shown below and a repeating unit structure represented by General Formula (3) shown below and has a structure in which a polymer produced by polymerization of styrenic, methacrylic or acrylic monomer is grafted to the side chain of the block copolymer;

wherein the polymerizable functional group that the block copolymer has on the side chain is in a content of 0.0001 to 50 mol % with respect to the entire block copolymer; and

wherein the styrenic, methacrylic or acrylic monomer that is graft polymerized to the block copolymer is in an amount of 0.1% by weight to 95% by weight in the toner;

General Formula (1)

wherein R⁰ represents —X—(COO-M)_r or —X—SO₃-M. X represents a linear, branched, or cyclic alkylene group having 1 to 20 carbon atoms, or —(CH(R⁵)—CH(R⁶)—O)_p—(CH₂)_m—CH_3-r— or —(CH₂)_m—(O)_n—(CH₂)_q—CH_3-r—, or a structure in which at least one methylene group thereof is substituted by a carbonyl group, oxygen atom or aromatic ring structure; r represents 1 or 2; p represents an integer from 1 to 18; m represents an integer from 0 to 35; n represents 1 or 0; q represents an integer from 0 to 17; M represents a hydrogen atom or a monovalent or multivalent cation; and R⁵ and R⁶ represent a hydrogen atom or an alkyl group, and R⁵ and R⁶ may be the same or different from each other,

General Formula (2)

wherein R¹ is selected from the group consisting of a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, -Ph, -Pyr, —(CH(R⁵)—CH(R⁶)—O)_p—R⁷ and —(CH₂)_m—(O)_n—R⁷, where a hydrogen atom in an aromatic ring may be substituted by a linear or branched alkyl group having 1 to 4 carbon atoms, and a carbon atom in an aromatic ring may be substituted by a nitrogen atom; p is an integer from 1 to 18; m is an integer from 1 to 36 and n is 0 or 1; R⁵ and R⁶ are each independently a hydrogen atom or —CH₃; R⁷ comprises a substance selected from the group consisting of a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, -Ph, -Pyr, —CHO, —CH₂CHO, —CO—CH═CH₂, —CO—C(CH₃)═CH₂ and —CH₂COOR⁸, provided that when R⁷ is other than a hydrogen atom, a hydrogen atom binding to a carbon atom in R⁷ can be substituted by a linear or branched alkyl group having 1 to 4 carbon atoms, —F, —Cl, or —Br, and a carbon atom in each aromatic ring can be substituted by a nitrogen atom; R⁸ is a hydrogen atom and an alkyl group having 1 to 5 carbon atoms; Ph represents a phenyl group and Pyr represents a pyridyl group,

General Formula (3)

wherein —OR² is selected from the group consisting of the following formulas:

—OCH₂CH₂OCOCH═CH₂,

—OCH₂CH₂OCOC (CH₃)═CH₂,

—OCH₂CH₂OCH₂CH₂OCOCH═CH₂, or

—OCH₂CH₂OCH₂CH₂OCOC (CH3)═CH₂.