The invention relates to a device (9) for locking a retractable roof of a motor vehicle (2), comprising: a strike (11) fixed to a lateral roof element (7a, 7b); a locking finger (12) pivotally mounted on a support (13) fixed to the front roof element (3) between an unlocked position and a locked position in which said finger (12) exerts on the strike (11) a force along a substantially vertical axis Z so as to press the lateral roof element (7a, 7b) towards its covering position in which it bears on the central element (6) and/or on the front element (3). The invention also relates to a locking system, a retractable roof and a vehicle equipped with such a device.