Abstract: The invention concerns a method for verifying the effectiveness at a given measurement location of a lightning ground system including at least one pick-up member connected to a ground conductor. The method includes the steps of feeding a current to at least one pick-up member by means of an injector device, measuring the magnetic field generated by the ground conductor at the measurement location using a detector device generating a measurement signal the amplitude of which is representative of the magnetic field, and comparing the amplitude of the measurement signal with a reference threshold corresponding to the amplitude of the measurement signal at a reference location a known distance from the ground conductor and in the field of protection of the lightning ground system in order to deduce therefrom, if the amplitude of the measurement signal is greater than the reference threshold, that the measurement location is in the field of protection of the lightning ground system.