He will now lead the ruling Liberal Democratic Party, replacing the outgoing and longest-serving Prime Minister of Japan, Shinzo Abe.
Former Prime Minister Shinzo Abe announced his resignation last month (August) due to ill health.
Most members of the new prime minister's cabinet include ministers from the Shinzo Abe era, with the foreign minister and finance minister continuing to hold office as before, while the new prime minister himself was in charge during Shinzo Abe's eight-year term.
