A cap transfer unit (1) comprising a cap transfer line (8) defining a transfer path (5) from a cap loading area (4) to a cap discharge area (6), and a cap pusher (16) slidingly mounted along the cap transfer line (8), the cap pusher (16) having a rest position in which the cap pusher (16) is spaced from the transfer path (5), and an active position in which the cap pusher (16) overlaps at least partially the transfer path (5) for coming into abutment with caps (2) located therein.