The Kazoku (華族, "Magnificent/Exalted lineage"; IPA: [ka̠zo̞kɯ̟]) was the hereditary peerage of the Empire of Japan, which existed between 1869 and 1947. It was formed by merging the feudal lords (daimyō) and court nobles (kuge) into one system modelled after the British peerage. Distinguished military officers, politicians, and scholars were occasionally ennobled as (新華族, shin kazoku, 'the newly ennobled'), until the country's defeat in the Second World War in 1945. The system was abolished with the 1947 constitution, which prohibited any form of aristocracy under it, but kazoku descendants still form the core of the traditional upper class in the country's society, distinct from the nouveau riche.

Kazoku (華族) should not be confused with kazoku (家族), which is pronounced the same in Japanese, but written with different characters, meaning "immediate family" (as in the film Kazoku above).

Following the Meiji Restoration of 1868, the ancient court nobility of Kyoto, the kuge (公家), regained some of its lost status. Several members of the kuge, such as Iwakura Tomomi and Nakayama Tadayasu, played a crucial role in the overthrow of the Tokugawa shogunate, and the early Meiji government nominated kuge to head all seven of the newly established administrative departments.

The Meiji oligarchs, as part of their Westernizing reforms, merged the kuge with the former daimyō (大名, feudal lords) into an expanded aristocratic class on 25 July 1869, to recognize that the kuge and former daimyō were a social class distinct from the other designated social classes of shizoku (士族, former samurai) and heimin (平民, commoners). They lost their territorial privileges. Itō Hirobumi, one of the principal authors of the Meiji constitution, intended the new kazoku peerage to serve as a political and social bulwark for the "restored" emperor and the Japanese imperial institution. At the time, the kuge (142 families) and former daimyō (285 families) consisted of a group of total 427 families.

All members of the kazoku without an official government appointment in the provinces were initially obliged to reside in Tokyo. By the end of 1869, a pension system was adopted, which gradually displaced the kazoku from their posts as provincial governors and as government leaders. The stipends promised by the government were eventually replaced by government bonds.

In 1884 the kazoku were reorganized and the old feudal titles were replaced with:

There were several categories within the kazoku. The initial rank distribution for kazoku houses of kuge descent depended on the highest possible office to which its ancestors had been entitled in the imperial court. Thus, the heirs of the five regent houses (go-sekke) of the Fujiwara dynasty (Konoe, Takatsukasa, Kujō, Ichijō and Nijō) all became princes, the equivalent of a European duke, upon the establishment of the kazoku in 1884.

The heads of eight other families (Daigo, Hirohata, Kikutei, Koga, Saionji, Tokudaiji, Ōinomikado and Kasannoin) all with the rank of seiga, the second rank in the kuge, became marquesses at the same time. Those family heads in the third tier of the kuge and with the rank of daijin became counts. Heads of families in the lowest three tiers (those in the ranks of urin, mei and han) typically became viscounts, but could also be ennobled as counts.