The invention relates to an instrument for treating biological tissue, including a housing, in which is disposed a ballistic device for generating extracorporeal shock wave-like pressure waves and a transfer element permanently placed on the biological tissue, said element coupling the pressure waves into the body of living creatures, wherein the transfer element couples non-focused, ballistically generated, shock wave-like pressure waves into the biological tissue, the waves generated by a striking member that is accelerated to a high final velocity of over 5 m/s by a pneumatic medium which is under an operating pressure in a pressure channel. A quick-acting valve releases the pneumatic medium, which is under working pressure, into the pressure channel, wherein a control circuit controls the duration of opening of the valve as a function of at least one or a combination of the following parameters: working pressure, impact frequency or pressure in the back-pressure chamber.
