Monarchy has shrinking royal population and few male successors. "The government will advance debate with respect for the resolution".
Concerns have recently grown over the sustainability of the male-only Imperial system, as the family now has only one young boy, Hisahito, 10. The law was needed because the 1947 Imperial House Law does not provide for abdication.
Under the law enacted Friday, an abdication, which will be Japan's first in 200 years, must take place within three years. Media reports have said officials are considering Akihito's abdication at the end of 2018, when Akihito turns 85 and marks 30 years on the throne, but no official date has been announced yet.
Akihito, 83, has had gone through a heart surgery and treatment for prostate cancer, and had told the public in a rare appearance past year that he feared age might make it hard for him to continue to fulfil his obligations.
The government will decide the timing of the abdication by issuing an ordinance.
"The emperor prefers the more casual image of himself as a "symbol" of the Japanese people", Kobayashi said.
While there was disagreement on how the Bill should be drafted - the opposition Democratic Party (DP) favoured a permanent revision - its passage was hardly in question given the Emperor's huge popularity, and after the ruling Liberal Democratic Party (LDP) stressed it would serve as a "legal precedent" for future abdications. The article states that the Emperor, who has advanced to the age of 83, is deeply concerned about it becoming hard for him to continue his activities as the symbol of the state, and that the people understand the Emperor's feelings and sympathize with them.
Akihito is officially barred from commenting on politics, but he has over the years hinted at his own anti-nationalist views.
The Emperor's Birthday national holiday will be changed from December 23 to February 23, the crown prince's birthday. Accordingly, annual budget for Prince Akishino's private expenses will increase threefold to 91.5 million yen ($833,000).
The emperor has no political powers since the country's defeat in World War II.
While on the throne, Emperor Akihito has often traveled with Empress Michiko to areas hit by natural disasters.
"Considering the ages of the Imperial family members, this is an important problem that we can not shelve", he said.
The special-case legislation is to be applied only to Akihito and enable his son Crown Prince Naruhito to succeed the Chrysanthemum Throne.