Japan has a relatively small number of infections compared to other countries, but there are concerns a sudden surge in cases in Tokyo could lead to a major outbreak in the world's biggest city.
In Tokyo there are now more than 1,000 confirmed cases, more than double the number a week ago.
The state of emergency would last about a month, Mr Abe said.
"In Japan, even if we declare a state of emergency, we will not close cities as seen in foreign countries.
Last week it was announced the Tokyo Olympic Games would start on 23 July, 2021 after being postponed for a year because of the coronavirus pandemic.