The present invention provides a pigment dispersant that exhibits high fine dispersibility, stability, and fluidity in a small amount, a pigment dispersion liquid including the pigment dispersant, and a process of producing the pigment dispersant and pigment dispersion liquid. The pigment dispersant contains as a main component, a graft copolymer formed through living radical polymerization using two or more monomers including a methacrylate A having an acidic group or a basic group and a methacrylate-based macromonomer B having a methacrylate residue at one terminal of a particular polymer chain that has a molecular weight of from 500 to 5000. A ratio of a total molar number of the methacrylate-based monomers relative to 1 mol of a polymerization-initiating compound in the raw material monomers is from 20 to 50 mol. A ratio of the B component-derived polymer chain to the graft copolymer is from 50 to 90 mass %.