The vote came after the 54-year-old former finance minister secured the leadership of the ruling Democratic Party in an election on August 29.

Ex-PM Naoto Kan, criticised for his handling of the March quake, formally resigned with his cabinet beforehand.

The new PM faces a daunting agenda, including trying to unify a divided party.

Large parts of Japan need to be rebuilt after March's earthquake and tsunami, and the crisis at the crippled Fukushima nuclear power plant still needs to be resolved.

Added to that, Mr Noda, a fiscal conservative, will need to address Japan's stagnant economy.

He has said in the past that he favours raising funds through increased taxation - including a doubling of Japan's sales tax, which currently stands at 5% - to cut debt and meet social security commitments.

On August 30 he said Japan faced problems with the high yen and with deflation.

Unlike Mr Kan, he wants Japan's halted nuclear reactors to be restarted and has not backed his call for a nuclear-free Japan.