This paper discusses harmonization to eliminate technical barriers and its influences on the nature of codes and standards system. By analyzing the EU Construction Products Directive, it identifies such principles concerning harmonized codes and standards system as; characteristics of a construction product may correlate to essential requirements through relationships among characteristics of works, and of parts/elements of them; They and products are managed by their own technical standards, consisting of goal, functions/performances, verifications and solutions; and, the correlation between essential requirements and a product may vary depending on the relationships between such notions included in each system.
