The device for detecting damage of a wind energy turbine of a wind energy turbine rotor blade, due to a lightning strike, comprises several magnetic or electric field sensors distributed along the length of a rotor blade of the wind energy turbine for measuring the magnetic or electric field concentration along the rotor blade and, an evaluation unit connected to the magnetic or electric field sensors for receiving the measured signals thereof, wherein damage of the wind energy turbine of the rotor blade caused by a lightning strike is calculated by the evaluation unit based on the measured concentration of the magnetic or electric field along the length of the rotor blade.