1. A method of estimating the subsurface structure of a target area by using waveform inversion of a seismic signal, the method comprising: defining an objective function for each damping constant based on a difference between measured data and modeled data of the subsurface structure in a transform domain; and defining an objective function for all damping constants by adding the objective function for each damping constant is normalized by applying a second weighting function, wherein the objective function for each damping constant is added after the objective function for each damping constant is normalized by applying a first weighting function.