To provide a written mark erasing liquid having high erasability of a mark clearly written with a writing ink having good color developing property, giving stable erased state resistant to the change with time, free from heavy metals, etc., having stability and excellent safety and rewritable on the erased part with the same writing ink.

The rewritable erasing liquid for erasing the mark written with a writing ink containing a dye decolorable with a reducing sulfur compound is at least composed of a reducing sulfur compound, a color redevelopment preventing agent and water.