Percussion device including a machine housing (1), a forwards and backwards movable percussion piston (2) in the machine housing, and a reciprocatingly movable tubular valve body (6) inside the machine housing, said percussion piston (2) being arranged to subject a tool (3) to impact, and said percussion piston including a first (4) and a second (5) driving surface arranged to be pressurized in order to drive the percussion piston forwards and backwards, said valve body (6) including a first end surface (12) and a second end surface (13), wherein pressurizing the first end surface (12) tends to drive the valve body in a first direction and pressurizing the second end surface (13) tends to drive the valve body in a second direction, whereby the valve body (6) is arranged, over a channel (7) arranged in the machine housing, to connect at least the second (5) of the driving surfaces alternately to a pressure source (8) or to low pressure (9), wherein an inner room (31) in the tubular valve body (6) is continuously connected to the low pressure (9) over at least one-opening (32) through an envelope surface of the valve body (6).