The invention relates to a connecting device which has a connecting element (18) of flat beam design fixed to a wiper blade (10) and an adapter (16) joined to said connecting element in an articulated manner, and also a joining element (14) that is joined to a wiper arm (12) and into the u-shaped cross-sectional profile of which the adapter (16) is inserted and, by means of a spring tongue (64) arranged on the top wall (42) thereof, is fixed to a pushbutton (66), the connecting element (18) having a central web (28) running in the longitudinal direction of the wiper blade (10) and bearing a hinge shaft (30) projecting on the long sides thereof, which is mounted in laterally flexible hubs (46) in side walls (40) of the adapter (16). According to the invention, the outwardly facing walls of the adapter (16), namely the side walls (40), the top wall (42), and the end walls (36, 62), have a general wall thickness of at least two millimeters, and the hubs (46) are to be formed as blind holes, the cylindrical surfaces of which form radial sliding surfaces (48) and the end faces of which form axial sliding surfaces (50), which are highly polished with an arithmetic mean roughness of Ra