Japan's Emperor Akihito is set to step down in April 2019, having announced last year that age and failing health might make it hard for him to fulfil his duties.
Prime Minister Shinzo Abe announced the timing of what will be the first abdication by a Japanese monarch in around two centuries.
It followed a meeting on Friday of the Imperial Household Council which includes lawmakers, royals and supreme court justices.
"This is the first abdication by an emperor in 200 years and the first under the (post-war) constitution," Abe told reporters after announcing the panel's recommendation.
"I feel deep emotion that today, the opinion of the Imperial Household Council was smoothly decided and a big step was taken toward the imperial succession."
Akihito, 84 this month, is due to abdicate on April 30 2019 with his heir, Crown Prince Naruhito, becoming emperor the next day.
As to who, in turn, will succeed Naruhito, 57, it is not set to be his child. That is because he has only a daughter, Princess Aiko, who turned 16 on Friday, and under current rules she will be prohibited from inheriting the males only throne.
Emperor Akihito, who has spent much of his nearly three decades on the throne seeking to soothe the wounds of World War Two, is deeply admired and respected in Japan which once considered its emperor to be divine.