Abstract: With the increased development of underground spaces in urban areas, ground subsidence has become an issue around the globe. In Korea, a law that specifies a systematic underground safety management procedure has been enacted with the goal of preventing ground subsidence accidents in urban areas. A number of methods can be used to find the fundamental cause of the occurrence of ground subsidence. Of these, a method based on GPR exploration has been actively studied in recent years. However, the GPR exploration method is significantly affected by the electromagnetic characteristics of the medium and the electromagnetic characteristics of various and complex elements of ground need to be analyzed through an accurate analysis of the ground subsidence mechanism. Therefore, in this study, GPR exploration simulation was conducted by analyzing the ground subsidence mechanism depending on the change in the groundwater level. In the sand layer, the boundary between the unsaturated and saturated ground showed a difference under high frequency, as electromagnetic waves were reflected due to the permittivity difference. Below the groundwater level, the attenuation of electromagnetic waves was large due to high electric conductivity. An underground cavity shape with a diameter of 0.5 m that is located 1.5 m below the ground showed a parabolic form. However, it was difficult to judge the presence of an underground cavity because a slight parabolic form was observed due to the overlapping of reflected signals when the vicinity of the underground cavity was relaxed depending on the change in the groundwater level.