Camshaft comprises an arrangement for hydraulically adjusting the relative position of rotation of the camshaft by influencing the control times of the valves. The arrangement includes a drive wheel (16) for the camshaft, a bucket wheel (17), and an impeller positioned with radial vanes in the cells of the bucket wheel. A locking device effective in the start phase of the internal combustion engine is provided between the bucket wheel and the impeller. The locking device comprises an axial spring-loaded hydraulic piston (37) positioned in one of the vanes of the impeller and a recess (40) for the piston. The piston protruding into the recess with a blocking section (39) and guided in a vane interacts with an operating element (44). The piston is loaded by a first pressure space and the operating element by a second pressure space. Preferred Features: The operating element is a bolt (47) which is guided on a stop (48) of the piston.
