The invention relates to a method and a device for controlling drilling parameters when drilling into rock with a drilling machine. During drilling, an impulse-generating device using an impact means is arranged to induce shock waves in a tool held against the rock, the said impulse-generating device being displaceable in the drilling direction relative to a supporting means, wherein a pressure level of a shock-wave-generating pressure is controlled during the drilling operation. A drilling speed of the said drilling is determined by determining a movement of the impulse-generating device with respect to the said supporting means, and the said shock-wave-generating pressure is controlled as a function of the said drilling speed that has been determined.