To markedly improve a dispersion property of an azo lake pigment for a lithographic ink which has poor water repellency because of its chemical structure and contains substances such as a rosin salt other than the pure pigment component, and to maintain the dispersion property of the azo lake pigment for the lithographic ink so as not to deteriorate with time.

The surface of the pigment particle is treated with an O/W emulsion comprising a specific mixed fatty acid monoester and a specific long-chain aliphatic alcohol as film-forming substances which can form a uniform continuous film on the surface of a primary particle of the azo lake pigment and contributes to marked improvement of the dispersion property and to retention of the dispersion property with time.