Coupling device (1) connecting a load carrier, associated with the device, to a ball of a towing hook assembled on a vehicle, which coupling device having a frame (2) including a first fixed connected coupling means (13) and an second movable connected coupling means (15), whereupon the movable coupling means by means of a clamping device (3) is transferable in the direction against the fixed coupling means, whereby a firm connection between the towing hook and the coupling device is achieved when the towing hook being embraced by the coupling means (13, 15), which have a curved shape adopted to said ball. According to the present invention is at least the movable coupling means (15) made of a plate, whose curved shape having an inner diameter, which is somewhat smaller than the diameter of the ball, and that the clamping device (3) abutting directly against the centre (21) of the curved shape of the movable coupling means, whereupon the clamping force act essentially against the midpoint of the ball.