Public holidays in Japan were established by the Public Holiday Law (国民の祝日に関する法律, Kokumin no Shukujitsu ni Kansuru Hōritsu^?) of 1948 (as amended). A provision of the law establishes that when a national holiday falls on a Sunday, the next working day shall become a public holiday, known as furikae kyūjitsu (振替休日^?, lit. "transfer holiday"). Additionally, any day that falls between two other national holidays shall also become a holiday, known as kokumin no kyūjitsu (国民の休日^?, lit. "citizens' holiday"). May 4, sandwiched between Constitution Memorial Day on May 3 and Children's Day on May 5, was an annual example of such a holiday until it was replaced by Greenery Day in 2007.

Prior to Japan's adoption of the Gregorian calendar in 1873, the dates of holidays were based on the traditional Chinese lunisolar calendar. As a result, New Year's Day, for example, was celebrated at the beginning of spring, as it is in modern China, Korea and Vietnam. Japan has 15 national, government-recognized holidays.