A chronological classification of Sangbok(상복) and Sibok(시복) for officers in Joseon Dynasty is proposed in this paper. The classification results in four distinct periods according to the usage of Sangbok and Sibok as well as their colers and naming: 1) the mixed usage period, 2) the usage-differentiation period, 3) the name-differentiation period, and 4) name-reversal period. During the mixed usage period which lasted until the early 15th century, Sangbok and Sibok were used with no distinction. In the usage-differentiation period, the King Sejong first made a regulation on the use of colors of Dal-lyung according to the occasion and black colored uniforms were used only for daily cabinet meetings. In the 16th century, the names of Sangbok and Sibok began to be used distinctively: Sangbok for formal clothing in black color and Sibok for ordinary clothing in pink color This period is defined as the name-differentiation period in this paper. In the name-reversal period f·hick begun around the 17th century, the usages as well as the colors of Sangbok and Sibok are totally reversed because of some confusions of the understanding on the previous government publications. However, the distinction of formal clothing and ordinary clothing remained.