Disclosed is a water-based ball-point pen ink composition which gives a smooth writing touch and shows various satifactory writing performance, comprising a colorant, water, and as an agent for imparting shear-thinning properties at least one member selected from sulfosuccinates represented by the following general formula (1):
wherein each R represents an alkyl or alkenyl group having 7 to 18 carbon atoms and X represents an alkali metal or an amine, the content of the at least one member being from 5 to 50% by weight.