Abstract: A fluid operated impact drilling device wherein a hammer is mounted in a casing for axial reciprocating movement and drilling fluid flows through the hammer. The flow of drilling fluid is controlled by a valve element at the upper portion of the hammer. Differential pressure areas are provided in the flow path of the drilling fluid which coupled with the action of the valve element causes the hammer to be repeatedly lifted up into the valve element and then driven downward against an anvil by the force of the drilling mud. The valve element remains partly open, thereby preventing excessive backpressures from damaging the drill pipe or equipment. The drilling device is attached immediately above the drill bit with the drill bit being secured to the anvil. A catcher device is mounted to stop the reciprocating impact action of the hammer against the anvil upon picking the bit up off bottom.