When stripping an optical fiber ribbon (7) from its polymer coating the ribbon is clamped at some distance from its end in a cutting and tension unit (3). When the lid (23) of this unit is folded down knifes are pressed into the coating at a side of the unit. The end portion of the ribbon (7) is then clamped in a heating unit (1) which before this clamping operation is moved, against the force from an elastically biased rod (31) extending from the cutting and tension unit, the movement being guided by guide rods (11), to be located directly at the side of the cutting and tension unit (3). The end of the ribbon in the heating unit is heated by a heating plate (5). When the end has become sufficiently hot and the coating is softened, the cutting and tension unit (3) automatically starts to move away from the heating unit (1) by the action of the elastically biased rod (31). Then the knifes start to separate the coating on the end portion from the rest of ribbon. The elastic force acts only to start the stripping movement, which is then fulfilled by manually pulling the units away from each other. The elastically biased rod (31) does not form any obstacle to this further movement since it acts with a free end surface at an opposite surface of the heating unit (1). By the elastic force the stripping operation is started at the right moment so that the end is soft enough but is not overheated.