As a result of Shang Yang's (商鞅) Reform, a new institution of nobility was constituted to substitute for the institution of Chou, under which the nobles were politically and militarily self-supported and economically independent. The power of the king of Chou inevitably declined, and conflicts between warring states occurred intermittently. It was regulated in the new institution of nobility that lieh hou (列侯) had no political and military power in his appendage, so the power of the central government could be built up practically. This new institution of nobility, accompanied with other reforms devised by Shang Yang, enhanced the warring capacity of the state of Ch'in. As a result, Ch'in defeated and ruined all other states, and founded the first empire with a centralized government in the history of China. After the fall of Ch'in dynasty, this new institution of nobility was adopted by Liu Pang (劉邦), the founder and first emperor of Han dynasty, and was practised throughout the Han dynasty. Because of the scarcity of historical materials of pre-Ch'in and Ch'in periods, the detail of this new institution of nobility had to be reconstructed upon knowledge obtained from materials of the Han dynasty. This study can be divided into two parts. The first part is an investigation into the detail of the institution of nobility itself, such as its beginning, substance, characteristics and variations. The second part is concerning the relationship between the institution of nobility and the political situation of the Han dynasty. Here is the first part published, it contains three divisions. The first is a short discussion of the origin of the institution of nobility of the Han dynasty, which can be traced back to Shang Yang's Reform. The second and third divisions try to find out the detail of the institution in the Han dynasty. The Han institution consists of 20 classes of chüeh (爵), of which the highest class was lieh hou. Lieh hou was ennobled by the emperor according to the regulation of a very strictly regulated code. lieh hou received from the Han government a great deal of benefits which included an appendage, called hou kuo (侯國 the state of lieh hou), the administrative unit at the same level with county. Lieh hou had no ruling power within his state. The minister of hou kuo, who was appointed and sent by the central government, did all the administrative duties of the state and also kept an eye on the conduct of lieh hou. However, lieh hou was still the ruler or the master of his enfeoffed state He possessed high social status and great economical benefits; he received taxes from people living in his state and his title as well as his state would be inherited by his son after his death. Lieh hou belonged to the noble class in Han dynasty, his social position was the highest besides the members of the royal family. The benefits and privileges of lieh hou were decreasing as time went on, especially after the Emperor Wu Ti (武帝). It is helpful to observe the development of absolute monarchism in China from this point of view.