This study is aimed at finding out the change process of Silla old office system(古官制) through bone-rank system(骨品制) and Office System(官制). In 520 Bupheung(法興) promulgated a code of administrative law that is believed to have delineated the seventeen-grade office rank structure, prescribed proper attire for the officialdom, and instituted the bone-rank system. Contents of office system and old office system were recoded in sacbokji(色服志) and chikgangji(職 官志) by samguksagi(三國史記). Old office system is consist of kumha(衿 荷)-sangdang(上堂)-chukwi(赤位)-daesa(大舍) etc. That was managed on before the system constructed, gradually make progress young(令)-kyung(卿)-daesa(大 舍)-sa(史) etc. This system was installed on 7years Bupheung, at first that were managed high level limited, finally the fragments of old office system were remained wihwabu(位和府), and sawonsungjion(寺院成典). As it were, this system translated after 5years Chinduk(眞德) lastly.