Abstract: A rock drill in which there is provided an impact unit, a front head with a tool holder and rotary drive means defined by a conventional pneumatic motor having a stator in the form of a cylindrical body, a rotor accommodated in said stator and having a symmetrical cam having a uniform convexo-concavo shape with lobes of said rotor cams being engaged with the inner cylindrical surface of the stator thereby forming chambers; spring-loaded vanes are accommodated in slots provided in the stator, with said vanes being engaged with the cam surface of the rotor and dividing the chambers into work chambers and idle chambers, the number of pairs of said vanes being one less than that of the chambers; each of the work chambers is in communication with channels supplying compressed air, while each of the idle chambers is in communication with channels leading to the atmosphere. Under the action of compressed air admitted into the work chambers, the rotor is rotated along with a drill bit attached thereto.