A device for separating the leading end of a new strip from the trailing end of a depleted strip during the renewal of a supply of strip material to a manufacturing machine, designed to operate in association with a changer device comprising feed means, means by which to cut the strip material and means by which the trailing end of the depleted strip is taken up and distanced, before reaching the cutting means, from a position in which the leading end of the new strip and the trailing end of the depleted strip are overlapped, wherein the separation is accomplished through the agency of detachment means stationed and operating between the feed means and the cutting means of the changer device and capable of movement between an at-rest position, outside the compass of the trajectory described by the strip material, and an operating position of insertion between the leading end of the new strip and the trailing end of the depleted strip, with the strips in motion, in such a way as to distance the two ends one from the other.