It is a crucial managerial issue how to manage assembly blocks at shipyard. Based on the project experience in Hyundai Heavy Industries, this study points out the difficulties on the block stockyard operations, formalizes the JIBUN (location) assignment problem for assembly blocks, and develops the JIBUN (location) assignment algorithm whose purpose is to reduce the number of unproductive block moves. Through simulation experiments for various situations, this study demonstrates the usefulness of JIBUN (location) assignment algorithm. In addition, this study examines the impacts of block move sequence rules and of block stockyard layouts on the block stockyard operations.