To clarify the mechanism of liberation in the comminution process of electronic scrap (e-scrap), we attempted to express the degree of liberation by first-order kinetic equation related to impact energy. Breakage energy measurements, comminution experiments, and discrete element method (DEM) simulations were conducted on two types of e-scrap with relatively simple structures. The mechanism of the liberation was estimated from the observation of the fractions in the comminution experiments. The results of the breakage energy measurements and DEM simulations supported the mechanism in terms of impact energy. The results of fitting first-order kinetic equations based on the cumulative specific impact energy from the DEM simulations and the degree of liberation in the experiments showed a high correlation. The fitting parameters of the firstorder kinetic equations were compared confirmed to be consistent with the mechanism of liberation and the breakage energy measurements, suggesting the numerical validity of the equations. In conclusion, it was shown that for e-scrap with relatively simple structures, the first-order kinetic equations of the cumulative specific impact energy calculated by DEM simulations can be used to evaluate the degree of liberation.