The invention relates to a sealing arrangement in a rotating control valve of a pressure fluid-operated percussion device, to which percussion device a tool is mountable movable in its longitudinal direction, the percussion device containing a work chamber and a transmission piston mounted movable to compress the tool suddenly to generate a stress pulse to the tool, inlet and outlet channels for conducting pressure fluid to the percussion device and away from it, and a control valve having a rotating switch member with channels to connect inlet and outlet channels through the channels of the switch member to alternately conduct the pressure fluid through the channels to the work chamber and, correspondingly, away from the work chamber, and in the inlet channel of the pressure fluid at the switch member side end thereof at least one sealing sleeve for the purpose of sealing the inlet channel to the switch member. In the arrangement, the sealing sleeve is mounted obliquely to the surface of the switch member and the switch member side surface of the sealing sleeve is essentially in the shape of the switch member surface.