In order to provide a thermosensitive decolorable ink composition which can readily be decolored with simple heating by rubbing and the like without using a microcapsule and is not developed again in color even after stored at very low temperature (−50° C. or lower) and which is excellent in stability with passage of time and has a vivid hue intensity, the above thermosensitive decolorable ink composition is provided with a constitution in which it contains as a colorant, color developing particles comprising at least a leuco dye, a developer and a crystalline substance and in which it further contains a decolorant comprising an amorphous resin.