The prediction of seismic rotational displacements in retaining walls under passive conditions is an important design aspect in earthquake-prone regions. In this study, a rotating block method was developed to calculate the rotational displacements of quay walls based on rigid foundations under seismic loading, and tsunami forces for the passive earth pressure condition. The proposed method considered the combined effects of seismic forces, hydrostatic, and hydrodynamic pressures and tsunami forces acting on the quay wall. The tsunami force was considered to be an additional force acting on the upstream face of the wall, and was calculated using a simple formula. Variations of different parameters involved in the analysis suggested the sensitiveness of the rotational displacements against the rotational slider of failure of the wall, which will provide a better guideline for design.