Japan's Imperial Household Agency says Empress Emerita Michiko has felt sick over the past several months probably because of mental stress.
The agency says the 85-year-old Empress Emerita vomited several times since mid-September and she was apparently bleeding from the stomach.
The agency adds that she is under medication and has not vomited for about a month.
This is the latest health problem for the Empress Emerita. The agency has disclosed that she suddenly lost weight from around April, and a blood test in June showed an increased level of a cardiac hormone that points to a high risk of heart failure.
Agency officials say these symptoms have not improved, and suggest that media reports about the Imperial family may have been one of the causes of the mental stress.
They say Emperor Emeritus Akihito's health condition has not changed and the couple will undergo regular checkups in the coming days.