The purpose of this study was to find out the origin of bonghwangdu(phoenix-head-ornaments) on bracketing units in Joseon period. For the purpose, early cases of bonghwangdu in dapo type and jusimpo type are analyzed at first. Second, architectural and cultural backgrounds of the ornaments on Joseon bracketing units are researched. And at last, the symbolic meanings of bonghwangs are compared with. The results of this study were as follows; bonghwangdu was probably decorated first in Buddhist buildings to simbolyze Garuda. it was originated around early 16th century, in jusimpo type bracketing units first, and adopted into dapo type bracketing units during mid and latter 16th century.