Abstract-This paper presents transient response behavior and frequency-dependent impedance of carbon ground module. The ground impedance of ground electrode was measured as a function of frequency of injected currents and simulated by using the distributed parameter circuit model with due regard to the frequency-dependent soil parameters, and the transient response behavior of the ground electrode against impulse current were investigated. It was found that the carbon ground module is effective in grounding system for lightning protection. The adequacy of the simulation technique and the distributed parameter circuit model for the ground electrode was verified. It is expected that the simulation methodology, which analyzes the frequency-dependent ground impedance of the carbon ground module proposed in this work, can be used in the design of a grounding system for protection against lightning.