PURPOSE: To provide a ball point ink compsn. which does not pick immediately after writing and can easily be erased with an eraser even after lapse of several days since writing, consisting of a linear polyurethane, a low-boiling solvent having a boiling point of not higher than a specified temperature and pigment particles.

CONSTITUTION: 100pts.wt. linear polyurethane (A), 70W300pts.wt. low-boiling solvent (B) having a b.p. of not higher than 200°C (e.g. benzene or acetone) and 80W130pts.wt. pigment particles (C) having a particle diameter of pref. 0.01W5μ (e.g. Pigment Yellow -1 or C.I. Vat Orange -3) are kneaded together to obtain the desired ball point ink compsn.