Change of era - Kaigen

Japanese: 改元 - かいげん

The era name that had been in use until that point is abolished and replaced with a new era name. There are five cases in which a new era name is started:

(1) A change of era name occurs when a new emperor reigns. There are cases in which an era name was changed on the day of an emperor's accession, such as Emperor Reiki (Emperor Gensho) and Emperor Jinki (Emperor Shomu) in the Nara period, but generally the era name is changed in the year following an emperor's accession or ascendance to the throne.

(2) A change of era name due to the appearance of an auspicious symbol. The first example was a change of era name from Taika to Taiho, Keiun, Wadou, etc. during the Asuka and Nara periods.

(3) A change of era name to avoid disasters such as natural disasters, epidemics, and wars. For example, a comet (Eiso) or an earthquake (Tengyo).

(4) The change of era name was made to avoid the difficulties of the Xinyou Revolution and the Jiashi Reformation, which were caused by the theory of divination. After the Engi era, it became customary to change the era name.

(5) Other changes of era names, such as those that took place at the start of a shogunate's reign after the Muromachi period.

When changing the era name, first a person in charge of era names was appointed, and each person was asked to submit several proposals for the new era name. After deliberation by the nobles (kugyo), the Emperor decided on the new era name and promulgated it by imperial edict. The new era name was used retroactively from the beginning of that year. In the Middle Ages, there were many cases of interference from the shogunate, and in the Edo period, the shogunate's prior approval was required, and the new era name was promulgated nationwide by the shogunate. When the era name was changed to Meiji, it was decided that one era name per emperor, and as stipulated in the old Imperial House Law, the Privy Council was consulted upon the accession to the throne, the Emperor calculated the name, and it came into effect on the same day. As the new Imperial House Law based on the Constitution of Japan omitted provisions regarding era names, the Era Name Law was enacted in 1979 (Showa 54), and the Cabinet was to decide the new era name only when a new emperor ascended to the throne.

[Yoshiaki Okada]

China

Emperors and feudal lords would change the era name to Yunen the year after their accession to count the years of their reign, but later, era names began to be changed during their reigns, and the practice of giving names to these dates began when Emperor Wu of Han designated 140 BC as the first year of Jianyuan. The first example of an era name being given was when the seventh year of that year was renamed Yuanguang. In China, era names were changed due to events such as Daishi, auspicious events, disasters, and revolutionary orders, but after the Yuan era, the system of one era name per emperor was generally maintained, with the era name only being changed to Daishi.

[Yoshiaki Okada]

[Reference] | One Emperor, One Era System | Era Name Law | Era Name

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

それまで用いられていた年号を廃して新しい年号にすること。改元には次の五つの場合がある。

(1)天皇の代始による改元。奈良時代の霊亀(れいき)（元正(げんしょう)天皇）、神亀(じんき)（聖武(しょうむ)天皇）など即位当日の改元例もあるが、一般には即位や践祚(せんそ)の翌年に改元される。

(2)祥瑞(しょうずい)の出現による改元。白雉(はくち)の出現による大化(たいか)からの改元を初例として、大宝(たいほう)・慶雲(きょううん)・和銅(わどう)など、飛鳥(あすか)・奈良時代に多い。

(3)天変地異、疫疾、兵乱などの厄災を避けるための改元。彗星(すいせい)（永祚(えいそ)）、地震（天慶(てんぎょう)）など。

(4)讖緯説(しんいせつ)による辛酉(しんゆう)革命、甲子(かっし)革令の年にあたってその難を避けるための改元。延喜(えんぎ)以後は恒例となった。

(5)その他、室町時代以後将軍の代始に行われた改元など。

　改元にあたってはまず年号勘者を定め、各人から幾通りかの新年号案を提出させ、公卿(くぎょう)の審議（難陳）を経て天皇が決定し、詔書をもって公布された。新年号はその年の年首にさかのぼって用いられた。中世には幕府の干渉を受けた場合が多く、江戸時代には幕府の事前の承認が必要とされ、新年号は幕府によって全国に公布された。明治の改元にあたって一世一元と定められ、旧皇室典範の規定により、践祚と同時に枢密院に諮詢(しじゅん)し、天皇が勘定して、即日施行された。日本国憲法に基づく新皇室典範には年号に関する規定が省かれたため、1979年（昭和54）に元号法が制定され、践祚があったときに限り内閣が定めることになった。

［岡田芳朗］

中国

天子、諸侯は即位の翌年に踰年(ゆねん)改元して治世年次を数えたが、のち治世の途中で改元することがおこり、これに名号をつけることは漢の武帝が紀元前140年を建元元年としたことに始まる。その7年を元光と改めたのが改元の初例である。中国においても代始、祥瑞、災異、革命革令などによって改元されたが、元(げん)以後はおおむね代始改元のみで一世一元制が守られた。

［岡田芳朗］

[参照項目] | 一世一元の制 | 元号法 | 年号

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