Puneet Varma (Editor)

Japanese era name

Updated on
Share on FacebookTweet on TwitterShare on LinkedInShare on Reddit
645–650  Taika
686–686  Shuchō
704–708  Keiun
650–654  Hakuchi
701–704  Taihō
708–715  Wadō

The Japanese era name (年号, nengō, "year name"), also known as gengō (元号), is the first of the two elements that identify years in the Japanese era calendar scheme. The second element, a number, counts the years since the era began; as in many other systems, there is no year zero. For example, the first year of the Heisei period was 1989 AD/CE, or "Heisei 1," so the year 2017 CE in this scheme is "Heisei 29".


As elsewhere in East Asia, the use of nengō was originally derived from Chinese Imperial practice, although the Japanese system is independent of the Chinese, Korean, and Vietnamese era-naming systems. Unlike some of these other similar systems, Japanese era names are still in use. Government offices usually require era names and years for official papers.

The four era names used since the end of the Edo period in 1868 can be abbreviated by taking the first letter of their romanized names. For example, S55 means Shōwa 55 (i.e. 1980), and H22 stands for Heisei 22 (2010). At 64 years, Shōwa is the longest era to date.


The system on which the Japanese era names are based originated in China in 140 BC, and was adopted by Japan in AD 645, during the reign of Emperor Kōtoku.

The first era name to be assigned was "Taika" (大化), celebrating the political and organizational changes which were to flow from the great Taika reform (大化の改新) of 645. Although the regular practice of proclaiming successive era names was interrupted in the late seventh century, it was permanently re-adopted in 701 during the reign of Emperor Monmu (697–707). Since then, era names have been used continuously up through the present day.

Historical nengō

Prior to the Meiji period, era names were decided by court officials and were subjected to frequent change. A new era name was usually proclaimed within a year or two after the ascension of a new emperor. A new era name was also often designated on the first, fifth and 58th years of the sexagenary cycle, because they were inauspicious years in Onmyōdō. These three years are respectively known as kakurei, kakuun, and kakumei, and collectively known as sankaku. Era names were also changed due to other felicitous events or natural disasters.

In historical practice, the first day of a nengō (元年, gannen) starts whenever the emperor chooses; and the first year continues until the next lunar new year, which is understood to be the start of the nengō's second year.

Era names indicate the various reasons for their adoption. For instance, the nengō Wadō (和銅), during the Nara period, was declared due to the discovery of copper deposits in Chichibu. Most nengō are composed of two kanji, except for a short time during the Nara period when four-kanji names were sometimes adopted to follow the Chinese trend. Tenpyō Kanpō (天平感宝), Tenpyō Shōhō (天平勝宝), Tenpyō Hōji (天平宝字) and Tenpyō Jingo (天平神護) are some famous nengō names that use four characters. Since the Heian period, Confucian thoughts and ideas have been reflected in era names, such as Daidō (大同), Kōnin (弘仁) and Tenchō (天長). Although there currently exist a total of 247 Japanese era names, only 72 kanji have been used in composing them. Out of these 72 kanji, 30 of them have been used only once, while the rest have been used repeatedly in different combinations.

Nengō in modern Japan

Mutsuhito assumed the throne in 1867, during the third year of the Keiō (慶応) era. On 23 October 1868, the era name was changed to "Meiji" (明治), and a "one reign, one era name" (一世一元, issei-ichigen) system was adopted, wherein era names would change only upon imperial succession. This system is similar to the now-defunct Chinese system used since the days of the Ming Dynasty. The Japanese nengō system differs from Chinese practice, in that in the Chinese system the era name was not updated until the year following the emperor's death.

In modern practice, the first year of a nengō (元年, gannen) starts immediately upon the emperor's ascension to the throne and ends on 31 December. Subsequent years follow the Gregorian calendar.

For example, the Meiji era lasted until 30 July 1912, when the Emperor died and the Taishō (大正) era was proclaimed. 1912 is therefore known as both "Meiji 45" and "Taishō 1" (大正元年, Taishō gannen), although Meiji technically ended on 30 July with Mutsuhito's death.

This practice, implemented successfully since the days of Meiji but never formalized, became law in 1979 with the passage of the Era Name Law (元号法, gengō-hō). Thus, since 1868, there have only been four era names assigned: Meiji, Taishō, Shōwa and Heisei, each corresponding with the rule of only one emperor. Upon death, the emperor is thereafter referred to by the era of his reign. For example, Mutsuhito is posthumously known as "Emperor Meiji" (明治天皇, Meiji Tennō).

It should be noted that it is protocol in Japan that the reigning emperor be referred to as Tennō Heika (天皇陛下, "His Imperial Majesty the Emperor") or Kinjō Tennō (今上天皇, "current emperor"). To call the current emperor by the current era name, i.e. "Heisei", even in English, is a faux pas, as this is—and will be—his posthumous name. Use of the emperor's given name (i.e., "Akihito") is rare, considered as vulgar behaviour, in Japanese.

Periods without era names

The era name system that was introduced by Emperor Kōtoku was abandoned after his death; no era names were designated between 654 and 686. The system was briefly reinstated by Emperor Tenmu in 686, but was again abandoned upon his death about two months later. In 701, Emperor Monmu once again reinstated the era name system, and it has continued uninterrupted through today.

Although use of the Gregorian calendar for historical dates became increasingly common in Japan, the traditional Japanese system demands that dates be written in reference to era names. The apparent problem introduced by the lack of era names was resolved by identifying the years of an imperial reign as a period.

Although in modern Japan posthumous imperial names correspond with the eras of their reign, this is a relatively recent concept, introduced in practice during the Meiji period and instituted by law in 1979. Therefore, the posthumous names of the emperors and empresses who reigned prior to 1868 may not be taken as era names by themselves. For example, the year 572—the year in which Emperor Bidatsu assumed the Chrysanthemum Throne – is properly written as "敏達天皇元年" (Bidatsu-Tennō Gannen, lit. "the first year of Emperor Bidatsu"), and not "敏達元年" (Bidatsu Gannen, lit. "the first year of Bidatsu"), although it may be abbreviated as such. By incorporating both proper era names and posthumous imperial names in this manner, it is possible to extend the nengō system to cover all dates from 660 BC through today.

Unofficial era name system

In addition to the official era name system, in which the era names are selected by the imperial court, one also observes—primarily in the ancient documents and epigraphs of shrines and temples—unofficial era names called shinengō (私年号), also known as ginengō (偽年号) or inengō (異年号). Currently, there are over 40 confirmed shinengō, most of them dating from the middle ages. Shinengō used prior to the reestablishment of the era name system in 701 are usually called itsunengō (逸年号). A list of shinengō and more information can be seen in the Japanese language entry on 私年号.

Because official records of shinengō are lacking, the range of dates to which they apply is often unclear. For example, the well-known itsunengō Hakuhō (白鳳) is normally said to refer to AD 650–654; a poetic synonym for the Hakuchi era. However, alternate interpretations exist. For example, in the Nichūreki, Hakuhō refers to AD 661–83, and in some middle-age temple documents, Hakuhō refers to AD 672–685. Thus, shinengō may be used as an alternative way of dating periods for which there is no official era name.

Other well-known itsunengō and shinengō include Hōkō (法興) (AD 591–621+), Suzaku (朱雀) (686), Fukutoku (福徳) (1489–92), Miroku (弥勒) (1506–7 or 1507–9) and Meiroku (命禄) (1540–43).

The most recent shinengō is Seiro (征露) (1904–5), named for the Russo-Japanese War.

Kyūshū nengō

Edo period scholar Tsurumine Shikenobu proposed that Kyūshū nengō (九州年号), said to have been used in ancient Kumaso, should also be considered a form of shinengō. This claim is not generally recognized by the academic community. Lists of the proposed Kyūshū nengō can be seen in the Japanese language entries 鶴峯戊申 and 九州王朝説.

Software support

Since the release of Java 8, the Japanese calendar is supported in the new Date and time API for the year Meiji 6 (1873) onwards.


Japanese era name Wikipedia