In order to provide a trailer coupling device for motor vehicles, comprising a rear-side cross member which is mountable on a vehicle body, a supporting unit provided on the cross member which holds a ball neck receiving sleeve having a ball neck receptacle in which a ball neck incorporating a coupling ball is insertable and fixable therein, in which the ball neck receiving sleeve is minimally visible and disturbing when the ball neck is not inserted, it is proposed that the supporting unit comprises a pivot bearing unit by means of which the ball neck receiving sleeve is pivotable from a working position in which the ball neck is insertable therein in order to use a trailer, into a rest position in which an insertion opening of the ball neck receiving sleeve is arranged outside a visible region.