PURPOSE: To provide the titled marking ink which produces clear writings on an impermeable writing board and is readily erasable, consisting of a pigment, a solvent-soluble resin, a volatile solvent and a nonionic surfactant made from edible oil and fat.

CONSTITUTION: A pigment, a solvent-soluble resin, a volatile organic solvent and a nonionic surfactant made from edible oil and fat are mixed for dispersion. The nonionic surfactant is incompatible with the resin and has a relatively low vapor pressure at around 230°C. It should pref. be used in an amount of 5W12% of the ink composition. The volatile organic solvent includes ketones, alcohols, and aromatic solvents and, for better results, two or more of the above solvents are blended.