A coupling device (1) for an agricultural machine (20) is disclosed having a support (2) for hitching to a tractor (3) and at least one arm (4) articulated to the support (2) and protruding from the support (2) in a direction parallel to the direction of advance (A) of the tractor (3). The arm (4) carries, an articulated manner, a chassis (6) carrying a work element (8) having a cutting angle relative to the ground. In order to allow fine control of the cutting angle during movements of the work element (8), the coupling device (1) also has an upper connecting-rod (17), a lower connecting-rod (18) and a central connecting-rod (19), each of the upper and lower connecting-rods (17, 18) articulated to the support (2) and the central connecting-rod (19) to form, projected in a vertical plane parallel to the direction of advance (A), a deformable quadrilateral, and the central connecting-rod (19) is articulated to the chassis (6). An agricultural machine (20) having the coupling device (1) is also disclosed.
