The tidal reclamation on the West Coast in the late Chosun Dynasty was conducted on the high-tidal flat where the ground is exposed for a long time. The effective way to acquire broader acres is to block the entrance of a bottleneck-shaped bay. In the case of the tidal reclamation to block the bottleneck penetrated by the tidal way, the scale of reclamation is larger. But technological process of this reclamation is more difficult and complex. Two key steps in large-scale tidal reclamation were the installation of the floodgate and then the blockage of the tidal way. The technology of large-scale tidal reclamation was based on human labor, and this feature persisted until the full-scale implementation of heavy equipment in the making of reclaimed land after the 1960’s. Because the demand for labor and materials increased along with the scale of reclamation, the range of social groups participating in large-scale reclamation was limited. In particular, large-scale reclamation required the capacity to mobilize large-scale labor within a short time period. These technological features of tidal reclamation can help to examine the reclamation projects in the late Chosun Dynasty.