A device for positioning a plate element (7a, 7b, 7c) in an infeed station (2) of a machine for treating the element (1), fitted with a conveyor (8, 9), gripping the element (7a, 7b, 7c) which is found in a predetermined intermediate position, and carrying the element (7a, 7b, 7c) in a rated running into successive processing stations (3, 4, 6). The device includes a holding device (18) for temporarily holding the element (7a, 7b, 7c), the holding device moving longitudinally alternatively (A) from an upstream position to a downstream position, and vice-versa, to pick up the element (7a, 7b, 7c) in a rear position and bring it to the intermediate position, and to return empty. A motor (23) moves the holding device (18) longitudinally, from the upstream position to the downstream position, and vice-versa, as a function of the rated running. A detector (27) detects a rear longitudinal position in which the element (7a, 7b, 7c) is found, and emits a position signal. The motor (23) is able to move (A, Aa, Ab, Ac) the holding device (18) from the upstream position to various downstream positions, as a function of the signal emitted by the detection device (27), so as to bring the element (7a, 7b, 7c) from the rear position to the intermediate position.