Mr. Abe, whose country faces a deep recession as the virus hinders trade and tourism, also announced an economic stimulus package worth nearly $1 trillion. He said that the government would suspend $240 billion in tax and social security payments and pay about $55 billion to households whose incomes have been affected by the pandemic.

The seven prefectures to be covered by the state of emergency, which Mr. Abe said would last about a month, are Chiba, Fukuoka, Hyogo, Kanagawa, Osaka, Saitama and Tokyo.

Under an emergency law enacted last month, Mr. Abe can ask prefectural governors to close schools, request that residents refrain from going out or holding events, and order building owners to contribute their facilities for medical use. He cannot issue stay-at-home orders or force businesses to close, as other countries have done.

Mr. Abe said that public transit would continue to run and that supermarkets would remain open.

Nearly three months into its outbreak, Japan is continuing to record new daily highs in confirmed infections, with the health ministry announcing 383 on Monday. Japan’s total number of cases has more than doubled, to 3,654, in the last eight days.

Japan has so far not reported the sort of explosive rise in cases that other countries have experienced, even though it has not taken aggressive steps like restricting people’s movements or testing widely for the virus. Its leaders have said for weeks that they have managed to contain the outbreak by quickly identifying clusters and tracing close contacts to infected people, but experts fear that the limited testing has allowed the virus to spread.

In remarks to reporters, Yoshihide Suga, Mr. Abe’s chief cabinet secretary, said that “in urban areas, including Tokyo, the number of infections is rapidly increasing, and the number of infections that cannot be tracked is increasing.”

In Tokyo on Sunday, the governor, Yuriko Koike, announced 143 new cases, a record high. By Monday evening, the city had announced an additional 83 cases. In all, Tokyo has reported more than 1,000 cases and 30 deaths.