A power steering device for a vehicle which is disposed in the transmission path between a steering handle and a steerable vehicle wheel, comprises a servo cylinder having two pressure chambers, which are separated by a working piston and are each connected to a pressure supply unit. A valve plunger, which seals a bypass channel between the pressure chambers, is movably disposed on the working piston. Furthermore, an adjustment bushing comprising an adjustment section is disposed in the servo cylinder, the valve plunger being moved against this section upon approaching an axial limit position, thereby opening the bypass channel. The adjustment bushing is clamped into the servo cylinder, yet held displaceably, wherein, on the adjustment bushing, a sealing section is provided, which is to be moved into a sealing position with the working piston so as to interrupt the flow connection between the pressure chambers.