The necessity of empirical determination of impact energy of hydraulic hammers prompted the Author to analyse the methods that had previously been used to determine this quantity. Based on the results of the analysis, the Author developed a new method of measurement of impact energy by means of force converter with an embedded elastic element, Taking into consideration the structural scheme and the principle of measurement, one derived analytical relationship that make it possible to calibrate the measuring system in energy units. A practical example of application of the developed system was in measurements of impact energy of hydraulic hammers used in Polish copper mining industry.