Abstract: A fluid powered stepping motor is disclosed for connecting to a pipe string to rotate a tool relative to the pipe string by raising and lowering the pressure in the pipe string. The motor includes a housing, the lower end of which is connected to the tool. A mandrel is connected to the pipe string and extends into the upper end of the housing to support the housing for rotation relative to the mandrel. A passageway extends longitudinally through the mandrel in fluid communication with the pipe string. A piston is located in and closes the passageway so that the piston will move downwardly in the passageway in response to fluid pressure in the passageway acting on the piston. Resilient spring resists the downward movement of the piston in the passageway, and cam members rotate the housing an incremental distance when the piston moves downwardly in the passageway.