Pigment dispersants, pigment dispersions and writing or recording pigment inks

A dispersant for organic pigments, comprising a compound represented by the following formula (I):

• wherein X and X′ each independently represent a hydrogen atom, a hydroxyl group, an alkoxy group, a primary, secondary or tertiary amino group, or an acylamino group;
• Y represents an anthraquinonylamino, phenylamino or phenoxy group, wherein said phenylamino and phenoxy have a hydrogen atom, a hydroxyl group, an alkoxy group, a primary, secondary or tertiary amino group, or an acylamino group at the 4-position or 5-position thereof;
• A and B each independently represent an alkyl group, a cycloalkyl group or an aryl group, and at least one of A and B has at least one substituent group containing a basic nitrogen atom;
• and Z represents a hydrogen atom, a cyano group, a halogen atom, an alkyl group, an alkoxy group, a nitro group, a benzoylamino group or a 3-benzoyl group, and said 3-benzoyl group may be fused together with X to form an acridone ring.