The invention is based on an adapter (16) for connecting a connecting element (30, 32, 34, 36, 38, 40) at the end of a wiper arm (18, 20, 22, 24, 26, 28) to a wiper blade (10) in particular of flat beam construction, wherein the adapter (16) has a base element (42). It is proposed that the base element (42) have a U-shaped cross-sectional profile which is formed from a base (56) and two side walls (48) and which, at that end side thereof which faces away from the wiper arm (18, 20, 22, 24, 26, 28), is closed off by a closure cap (44), that spring arms (68) be integrally formed on the side walls (48) of the base element (42), which spring arms (68) extend in the longitudinal direction (124) toward the closure cap (44), engage into the latter and latch with buttons (70) into cutouts (84) which are provided in side walls (82) of the closure cap (44), and in that longitudinally directed bars (78) are arranged on the inner sides of the side walls (82) of the closure cap (44), which bars (78) are guided in a movable manner in cutouts (60) of the side walls (48) of the base element (42) when the buttons (70) are released, and which bars, in the closed state, block transversely running assembly gaps (62) and close off receiving chambers (66) for locking cams (104, 120).