I studied the egg-laying behavior of the frog Buergeria japonica in the coastal areas of Okinawa, Japan, to clarify whether females avoid high salinity areas to reduce egg mortality. I compared the distribution of oviposition sites to the salinity gradient and evaluated the physical cues used by females to select oviposition sites. Females selected oviposition sites above the high tide line at spring tide, where eggs would not be disturbed by incursion of seawater. Above this high tide line, females selected oviposition sites from which eggs would not be washed out or desiccate, by using cues such as water depth and substrate. Examination of conditions at two spatial scales helps to clarify the evolution of oviposition site selection.