A device (1) for feeding self-adhesive or “pressure sensitive” labels to a labelling machine comprises a frame (2) and supporting means (3) comprising a supporting plate (17) for supporting a reel (4) of web (5) with labels applied to it, and also comprises at least one guide element (28, 29) designed to be at least partly inserted in a central hole (7) of the reel (4) which can rotate about it. The device (1) also comprises a detaching station (8) for detaching the labels from the web (5), feeding means (9) for feeding the web (5) to the detaching station (8) and recovery means (10) for recovering the web (5) without labels. The supporting plate (17) is removably associated with the frame (2) and the supporting means (3) also comprise a containment head (30) switchable between an open configuration, in which it allows the coupling with and uncoupling from the frame (2) of the supporting plate (17), with the reel (4) placed on it, and an operating configuration, in which it allows the reel (4) to be held between itself and the supporting plate (17), allowing reel (4) rotation.