A retractable writing/erasing piece against sliding back includes a holding pipe, an internal pipe, a sleeve pipe, a slide base and a writing/erasing piece. At least a pair of stepped guide grooves is disposed on a pipe wall of the internal pipe and the stepped guide grooves have multiple guide groove windows. At least a pair of spiral guide slots is disposed on an internal wall of the sleeve pipe. At least a pair of guide protrusions is disposed on the slide base. The pair of guide protrusions is contained in the pair of spiral guide slots. The guide protrusions are abutted against a blocking wall of a guide groove window therein, so that an accident sliding back of the writing/erasing piece and the slide base can be avoided.