The invention relates to an emergency cutting device (1) for vehicle safety belts, characterised in that it comprises locking means (6,7), acting on a safety belt (3) so as to put the same under tension; means (8) for cutting said safety belt (3); and operation means (12, 13), operatively connected with said locking means (6, 7) and with said cutting means (8); said operation means (9, 10) activating in succession said locking means (6, 7) and said cutting means (8), so as to cut said safety belt (3), and then deactivating said locking means (6, 7) thus freeing said safety belt (3) and then the user of the same.