An Imperial Household Agency spokesman said Akihito's address, via video, would be broadcast at 3:00 PM (0600 GMT) on Monday.
The 82-year-old, who has been suffering from health problems for years, was not expected to announce explicit plans to step down, as he is constitutionally barred from making political statements.
"The emperor will express his feelings regarding his duties as a symbol" of the nation, the spokesman told AFP.
But Japanese media, including public broadcaster NHK, have widely reported that Akihito would likely hint at his desire to abdicate the Chrysanthemum Throne.
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The reports came as a surprise to many in Japan where the last abdication happened more than 200 years ago.
Akihito, who has suffered from prostate cancer and heart problems in recent years, spoke of his growing limitations last year.
He acknowledged making "mistakes" in his duties, which range from native Shinto religious ceremonies to visiting residents in regions hit by Japan's frequent natural disasters.
Akihito's second son, Prince Akishino, a few years ago suggested that emperors should be allowed to retire.
The possible abdication is a complicated and sensitive issue in Japan, where current laws put in place after World War II made the emperor the "symbol of the state" with no provisions for one to step down.
But the highly choreographed event on Monday could well set a process in motion to change the law.
The video message would be uploaded on the Imperial Household Agency's website and shown on television, Kyodo News agency reported today.