In this study, according to drainage condition(undrained and drained) in soil, the settlement and horizontal displacement of caisson quay wall and apron in Youngilman port were estimated which was occurred due to earthquake-induced excess pore water pressure with the magnitude of 5.4 earthquake in Pohang on November 15, 2017. In general, seismic response analysis was carried out under undrained drainage condition, but in this study, drain drainage analysis was conducted to estimate displacement during earthquake as well as an additional displacement due to dissipation of excess pore water pressure after earthquake. These results of after earthquake can not be known under undrained drainage condition. Results clearly showed that the behavior of structure and ground was dependent on drainage condition in soil. Especially, based on the drained drainage condition, the additional displacement was clearly detected due to dissipation of excess pore water pressure after earthquake. Which indicates that both results are different from drainage condition in soil, and therefore, drained condition analysis is necessary to accurately estimate the behavior of ground and structure in seismic response analysis.