Ansei (安政) was a Japanese era name (年号,, nengō,; lit. "year name") after Kaei and before Man'en. This period started in November 1854 and ended in March 1860. During this time, the emperor was Kōmei-tennō (孝明天皇).
The nengō Ansei means "tranquil government".

| Ansei | 1st | 2nd | 3rd | 4th | 5th | 6th | 7th |
|---|---|---|---|---|---|---|---|
| 1854 | 1855 | 1856 | 1857 | 1858 | 1859 | 1860 |
| Preceded by: Kaei |
Era or nengō: Ansei |
Succeeded by: Man'en |