Classification of submerged objects can be performed using broadband sonar and underwater sound scattering analysis. The backscattered signals, composed of specular echo and elastic echo, have information on the submerged target, including its dimensions and material characteristics. In this study, we performed shockwave-scattering simulations of backscattered signals when a broadband shockwave (1–60 kHz) was used as the incident wave. The radius and thickness of a cylindrical target was estimated by analyzing the echo signal in the time domain and the echo spectrum in the frequency domain. The validity of the estimated parameters was confirmed by the modeling results.