PURPOSE: The titled ink composition most suitable for a marking pen for slender writing, having a preventing effect on dryness of pen tip, causing neither blotting nor running to the reverse, comprising a direct dye as a main component and a specific amount of glycerol acetic ester as a dryness inhibitor.

CONSTITUTION: A direct dye as a dyestuff component, and, if necessary, other dye, e.g., acidic dye and 2W50wt%, preferably 5W25wt% glycerol acetic ester (e.g., monoacetin, diacetin, triacetin, etc.) alone, or its mixture of two or more of the esters, as a dryness inhibitor are added to ink, to give the desired ink composition. For example, an alcohol, a surface active agent, antiseptic, etc. may be added to the composition.