An erasable ink composition for writing on an impervious writing surface comprising an organic solvent, a resin, a pigment, and a separating agent which comprises:(a) a polyoxyethylene polyoxypropylene block copolymer, as a first separating agent, which is liquid at normal temperatures in an amount of 5-20% by weight, and(b) at least one organic compound selected from the group consisting of a carboxylic acid ester, a polyoxypropylene monoalkyl ether and a polyoxyethylene polyoxypropylene monoalkyl ether, as a second separating agent, which is liquid at normal temperatures in an amount of 2-10% by weight.