PURPOSE: A printing ink, consisting of a homogeneous mixture system of a phospholipid, fatty oil and unsaturated fatty acid in a specific composition ratio, easily available, capable of giving a clear printing, hue, saturation, and printing letters, patterns, etc. on the surface of a tablet-shaped material, e.g. a food or medicine.

CONSTITUTION: A printing ink of a homogeneous mixture system, prepared by incorporating (A) 70W20wt% phospholipid with (B) 30W80wt% fatty oil, e.g. rapeseed oil, sesame oil, saury oil or whale oil, and/or unsaturated fatty acid, e.g. oleic acid or linoleic acid, and if necessary incorporating a food dye therein.