A stationery tool has a body and a rubber holding device. The body has a holding end and a holding recess defined in the holding end. The rubber holding device is detachably or securely mounted in the holding recess for holding a rubber to adjust an extension length of the rubber relative to the body and has a clamping segment and a guiding segment. The clamping segment has multiple clamping protrusions for pressing against the rubber. The guiding segment extends outwardly and makes an opening of the rubber holding device have a distance from the clamping segment. Accordingly, the stationery tool has capabilities of adjusting an extension length of the rubber and conveniently replacing a used rubber.