Abstract: A writing medium capable of being erased by merely mechanically rubbing with an ordinary pencil eraser after writing and capable of forming a drawing line possessing high adhering strength onto the surface of paper even immediately after writing on the paper. The writing medium contains a pigment as a colorant, a polynorbornane and/or trans-1,4-polyisoprene, and a mixture solvent solution for dissolving the polynorbornane and the trans-1,4-polyisoprene and containing a low boiling point organic solvent having a boiling point of less than 180.degree. C. and a high vaporization rate and operating as a plasticizer for the polynorbornane and the trans-1,4-polyisoprene and a high boiling point organic solvent having a boiling point of higher than 300.degree. C. and a low vaporization rate. Thus, a drawing line written with the writing medium can be erased merely by rubbing with the eraser within several hours after writing, and is not erased thereafter.