Stabilization of the seawalls is required for protecting the important facilities along the coast of the Fukui Port. Since 2004, Ministry of Land, Infrastructure and Transport has commenced the projects for improvement of the existing seawalls for scouring and liquefaction protection, and for construction of new submerged breakwaters. Construction of “two-crested submerged breakwaters, ” which have two parallel crests along the coast, was newlycommenced in 2006. The ministry realized that stability of the submerged breakwater needs to be examined because the submerged breakwater experiences winter stormy waves while the construction of the breakwater is not yetcompleted, i. e., the total length of the breakwater is 45m compared to the designed total length of 200m. This paper presents a survey result of location of concrete armor blocks for the submerged breakwater on partial completion with using Real-Time-Kinematic GPS.